uk.co.hopi/hopi

Measured conclusion: Deep-tested. L2 outcome: tools_ok.

Free UK calculators, converters and validators (tax, VAT, stamp duty, dates, units), read-only.

Add to your agent

Copy this into your MCP client config:

{
  "mcpServers": {
    "hopi": {
      "url": "https://mcp.hopi.co.uk/mcp",
      "transport": "streamable-http"
    }
  }
}

Measured tools (207)

• hopi_add_working_days read-only

  Add or subtract a number of working days (Monday to Friday) from a start date, optionally skipping England and Wales bank holidays. Dates use the YYYY-MM-DD format. Bank holiday data covers 2026 and 2027 only, so outside those years just weekends are skipped. Source: https://hopi.co.uk/add-working-days/

  Parameters:

  • start (required) — string — Start date in YYYY-MM-DD format
  • days (required) — integer — Number of working days to move (0 to 100000)
  • direction — string — 'add' to count forwards, 'sub' to count backwards (default 'add')
  • bankHolidays — boolean — Also skip England and Wales bank holidays, not just weekends (default true)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_age_calculator read-only

  Work out an exact age from a date of birth, as of today or an optional 'as of' date. Dates use the YYYY-MM-DD format. Returns the age in years, months and days, the total days lived, and the next birthday. Source: https://hopi.co.uk/age-calculator/

  Parameters:

  • dob (required) — string — Date of birth in YYYY-MM-DD format
  • asOf — string — Optional date to measure the age at, in YYYY-MM-DD format (defaults to today)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_ai_prompt_builder read-only

  Build a well-structured prompt to paste into an AI chatbot or image generator. Give the task plus any of: the role the AI should take, background, audience, tone, format, length, things to avoid, an example of good output, and material to work on (for summarise, analyse and code tasks). taskType image switches to style, lighting, composition and aspect ratio instead. target formats the prompt for 'chatgpt' (Markdown headings, the task repeated after long material, as OpenAI's guidance suggests), 'claude' (XML tags with long material first and the task last, as Anthropic recommends), 'gemini' (Markdown with the question after the context, as Google recommends) or 'any'. Returns the prompt, a checklist of which parts are present, vague words found, and the word count with a rough token estimate (characters divided by 4). Nothing is sent to any AI. Source: https://hopi.co.uk/ai-prompt-builder/

  Parameters:

  • task (required) — string — What the AI should do (for images: what the image should show)
  • role — string — Who the AI should be, e.g. 'A UK consumer rights adviser'
  • tone — string — Tone of voice
  • avoid — string — Things the AI should avoid
  • style — string — Image style (image tasks only)
  • format — string — Output format
  • length — string — Length: one sentence, one short paragraph, under 100/250/500 words, about 1,000 words, or as long as it needs
  • target — string — Which AI to format the prompt for; default any (ignored for images)
  • context — string — Background the AI needs: the situation, facts and figures
  • example — string — A short example of what good output looks like
  • audience — string — Who the result is for
  • language — string — Programming language and tools (code tasks only)
  • lighting — string — Lighting and mood (image tasks only)
  • material — string — Text, data or code to work on (used for summarise, analyse and code)
  • taskType — string — Kind of task; default write
  • aspectRatio — string — Image aspect ratio (image tasks only)
  • composition — string — Composition and camera, e.g. 'close-up, low angle' (image tasks only)
  • askQuestions — boolean — Ask the AI to ask clarifying questions before it starts
  • explainReasoning — boolean — Ask the AI to explain its main choices after answering

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_alcohol_unit_calculator read-only

  Work out UK alcohol units in a drink from its ABV (percentage) and volume (millilitres), using units = ABV x ml / 1000. Optionally give the number of those drinks per week to get a weekly total compared against the NHS low risk guideline of 14 units a week. Source: https://hopi.co.uk/alcohol-unit-calculator/

  Parameters:

  • abv (required) — number — Alcohol by volume as a percentage, e.g. 12 for 12% wine
  • ml (required) — number — Volume of the drink in millilitres, e.g. 175 for a medium glass of wine
  • drinksPerWeek — number — Optional number of these drinks per week, to work out a weekly units total

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_alphabetical_order read-only

  Sort the lines of a block of text into alphabetical order. Blank lines are dropped. Uses natural en-GB ordering so numbers within lines sort sensibly. Can sort ascending (A to Z) or descending (Z to A), and can ignore case. Source: https://hopi.co.uk/alphabetical-order/

  Parameters:

  • text (required) — string — The text to sort, one item per line
  • direction — string — 'asc' for A to Z (default), 'desc' for Z to A
  • caseInsensitive — boolean — Ignore letter case when sorting (default false)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_angle_converter read-only

  Convert an angle from one unit to another. Units: deg (degrees), rad (radians), grad (gradians), turn (full turns). Source: https://hopi.co.uk/angle-converter/

  Parameters:

  • value (required) — number — The angle value to convert
  • from (required) — string — Unit to convert from
  • to (required) — string — Unit to convert to

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_area_converter read-only

  Convert an area from one unit to another. Units: sqm (square metres), sqft (square feet), sqyd (square yards), acre (acres), ha (hectares), sqkm (square kilometres), sqmi (square miles). Source: https://hopi.co.uk/area-converter/

  Parameters:

  • value (required) — number — The area value to convert
  • from (required) — string — Unit to convert from
  • to (required) — string — Unit to convert to

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_aspect_ratio_calculator read-only

  Aspect ratio helper. In 'simplify' mode, give width and height to get the simplified W:H ratio, decimal ratio and nearest common ratio. In 'solve' mode, give a ratio (ratioW:ratioH) plus one of width or height to get the missing side. Source: https://hopi.co.uk/aspect-ratio-calculator/

  Parameters:

  • mode (required) — string — 'simplify' a width and height, or 'solve' a missing side from a ratio
  • width — number — Width in pixels or units (simplify mode, or the known side in solve mode)
  • height — number — Height in pixels or units (simplify mode, or the known side in solve mode)
  • ratioH — number — Ratio height part, e.g. 9 (solve mode)
  • ratioW — number — Ratio width part, e.g. 16 (solve mode)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_average_calculator read-only

  Work out the mean, median, mode, sum, count, minimum and maximum of a list of numbers. Provide the numbers separated by spaces, commas, semicolons or new lines (type 1200 rather than 1,200, as commas are treated as separators). Source: https://hopi.co.uk/average-calculator/

  Parameters:

  • numbers (required) — string — A list of numbers separated by spaces, commas, semicolons or new lines

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_base32_encoder read-only

  Encode text to RFC 4648 Base32 or decode Base32 back to text. Encoding maps the UTF-8 bytes of the text into 5-bit groups using the alphabet A to Z then 2 to 7, padded to a multiple of 8 characters with equals signs. Decoding tolerates lowercase input and missing padding, and reports characters outside the alphabet as an error. Source: https://hopi.co.uk/base32-encoder/

  Parameters:

  • text (required) — string — The text to encode, or the Base32 string to decode
  • mode — string — 'encode' turns text into Base32, 'decode' turns Base32 back into text (default encode)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_base64 read-only

  Encode text to Base64, or decode a Base64 string back to text. UTF-8 safe, so accents and emoji survive the round trip. Returns the converted text or a clear error. Source: https://hopi.co.uk/base64/

  Parameters:

  • text (required) — string — The text to encode, or the Base64 string to decode
  • mode (required) — string — 'encode' text to Base64, or 'decode' Base64 back to text

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_bill_splitter read-only

  Split a restaurant bill between people. In 'itemised' mode, list each item with its amount and who shared it, then add an optional tip and service charge (both percentages applied to each person's own share). In 'even' mode, split one total evenly with an optional tip. Amounts in GBP. Source: https://hopi.co.uk/bill-splitter/

  Parameters:

  • mode (required) — string — 'itemised' splits by item and who had it; 'even' splits one total equally
  • items — array — Itemised mode: each item with its amount and the names who shared it. An item with no names is shared by everyone.
  • total — number — Even mode: the bill total before tip
  • people — array — Itemised mode: names of the people sharing the bill
  • tipPercent — number — Tip as a percentage (default 0)
  • peopleCount — integer — Even mode: number of people to split between
  • servicePercent — number — Itemised mode: service charge as a percentage (default 0)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_bingo_card_generator read-only

  Generate one or more UK 90-ball bingo cards. Each card is a 3-row by 9-column grid holding 15 numbers, 5 per row, with each column drawing from its own decade (1 to 9, 10 to 19, and so on up to 80 to 90). Blank squares are null. Source: https://hopi.co.uk/bingo-card-generator/

  Parameters:

  • count — integer — How many cards to generate, 1 to 100 (default 1)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_bitcoin_address_validator read-only

  Check whether a Bitcoin address is valid by verifying its checksum and structure. Supports legacy Base58Check (P2PKH, P2SH) and Bech32/Bech32m SegWit and Taproot addresses, on mainnet and testnet. Does not query the blockchain or check balances. Source: https://hopi.co.uk/bitcoin-address-validator/

  Parameters:

  • address (required) — string — The Bitcoin address to validate

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_bmi_calculator read-only

  Work out body mass index (BMI) from height and weight, with the NHS weight category. Use units 'metric' with heightCm and weightKg, or 'imperial' with heightInches and weightPounds. BMI = weight in kg / (height in metres squared). Source: https://hopi.co.uk/bmi-calculator/

  Parameters:

  • units (required) — string — 'metric' (cm and kg) or 'imperial' (inches and pounds)
  • heightCm — number — Height in centimetres (metric)
  • weightKg — number — Weight in kilograms (metric)
  • heightInches — number — Total height in inches (imperial)
  • weightPounds — number — Weight in pounds (imperial)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_body_fat_calculator read-only

  Estimate body fat percentage using the US Navy tape method from a few measurements. For males give height, neck and waist; for females give height, neck, waist and hip. Use units 'metric' (centimetres) or 'imperial' (inches). Optionally give weight (kg for metric, pounds for imperial) to also get fat mass and lean mass in kilograms. Source: https://hopi.co.uk/body-fat-calculator/

  Parameters:

  • sex (required) — string — Biological sex, determines the formula and whether hip is needed
  • units (required) — string — 'metric' (cm) or 'imperial' (inches)
  • height (required) — number — Height (cm if metric, inches if imperial)
  • neck (required) — number — Neck circumference (cm if metric, inches if imperial)
  • waist (required) — number — Waist circumference (cm if metric, inches if imperial)
  • hip — number — Hip circumference, females only (cm if metric, inches if imperial)
  • weight — number — Optional weight (kg if metric, pounds if imperial) for fat and lean mass

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_caesar_cipher read-only

  Encode or decode text with a Caesar shift cipher. Each letter is moved along the alphabet by the shift amount; a shift of 13 is ROT13. Only A to Z letters are changed, everything else is left as is. Decoding applies the opposite shift. Source: https://hopi.co.uk/caesar-cipher/

  Parameters:

  • text (required) — string — The text to transform
  • shift (required) — integer — How many places to shift each letter (e.g. 3, or 13 for ROT13)
  • mode — string — 'encode' to apply the shift, 'decode' to reverse it (default encode)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_cagr_calculator read-only

  Work out the compound annual growth rate (CAGR) that takes a starting value to an ending value over a number of years. Returns the annual rate, the total growth and the growth multiple. Source: https://hopi.co.uk/cagr-calculator/

  Parameters:

  • start (required) — number — Starting value (must be greater than zero)
  • end (required) — number — Ending value
  • years (required) — number — Number of years over the period (may be a fraction)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_calories_to_kj read-only

  Convert food energy between kilocalories (kcal) and kilojoules (kJ) using the exact factor 1 kcal = 4.184 kJ. Give an amount and its unit ('kcal' or 'kj'); returns both values. Source: https://hopi.co.uk/calories-to-kj/

  Parameters:

  • amount (required) — number — The energy amount to convert
  • unit (required) — string — The unit of the amount: 'kcal' (kilocalories) or 'kj' (kilojoules)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_case_converter read-only

  Convert text to a different letter case. 'upper' is UPPERCASE, 'lower' is lowercase, 'title' capitalises the first letter of each word, and 'sentence' capitalises the first letter of each sentence. Source: https://hopi.co.uk/case-converter/

  Parameters:

  • text (required) — string — The text to convert
  • mode (required) — string — The target case

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_cat_age_calculator read-only

  Convert a cat's age in years to an approximate human age, using the standard 15, 24, then 4 a year chart. Returns the human-equivalent age and the cat's life stage. Source: https://hopi.co.uk/cat-age-calculator/

  Parameters:

  • catAge (required) — number — The cat's age in years (0 to 40)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_celsius_to_fahrenheit read-only

  Convert a temperature between Celsius and Fahrenheit. Also returns Kelvin. Set direction to 'c-to-f' or 'f-to-c'. Source: https://hopi.co.uk/celsius-to-fahrenheit/

  Parameters:

  • value (required) — number — The temperature value to convert
  • direction (required) — string — 'c-to-f' converts Celsius to Fahrenheit, 'f-to-c' converts Fahrenheit to Celsius

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_character_counter read-only

  Count the characters in a block of text, including a count with spaces removed, the word count, how many SMS messages it would take to send, and the Twitter/X characters remaining out of 280. Source: https://hopi.co.uk/character-counter/

  Parameters:

  • text (required) — string — The text to measure

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_cipher_identifier read-only

  Identify what encoding or classical cipher a piece of text probably is (Base64, Base32, hex, binary, octal or decimal ASCII, URL encoding, HTML entities, Morse, Caesar or ROT-N, Atbash, reversed text) or recognise it as a UUID, IPv4 address, Unix timestamp, JWT or hash digest. Returns ranked candidates with confidence and a decoded preview, then auto-decodes nested layers (up to 8) while a step is at least 60% confident. Cannot break keyed encryption such as AES. Source: https://hopi.co.uk/cipher-identifier/

  Parameters:

  • text (required) — string — The unknown text to identify and decode

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_cm_to_feet read-only

  Convert a height between centimetres and feet/inches. Direction 'cm-to-feet' takes cm and returns feet and inches. Direction 'feet-to-cm' takes feet and inches and returns cm. Source: https://hopi.co.uk/cm-to-feet/

  Parameters:

  • direction (required) — string — Which way to convert
  • cm — number — Centimetres (for cm-to-feet)
  • feet — number — Feet (for feet-to-cm)
  • inches — number — Inches (for feet-to-cm, optional)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_cmyk_to_rgb read-only

  Convert print CMYK values (each 0 to 100) to on-screen RGB and hex, or convert RGB (each 0 to 255) the other way to CMYK. Uses the standard device-independent conversion. Source: https://hopi.co.uk/cmyk-to-rgb/

  Parameters:

  • mode (required) — string — Direction of conversion
  • b — integer — Blue 0 to 255 (for rgb_to_cmyk)
  • c — number — Cyan 0 to 100 (for cmyk_to_rgb)
  • g — integer — Green 0 to 255 (for rgb_to_cmyk)
  • k — number — Key/black 0 to 100 (for cmyk_to_rgb)
  • m — number — Magenta 0 to 100 (for cmyk_to_rgb)
  • r — integer — Red 0 to 255 (for rgb_to_cmyk)
  • y — number — Yellow 0 to 100 (for cmyk_to_rgb)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_coin_flip read-only

  Flip a fair coin one or more times. Returns each result plus a tally of heads and tails. Source: https://hopi.co.uk/coin-flip/

  Parameters:

  • count — integer — How many coins to flip, 1 to 10000 (default 1)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_colour_name_finder read-only

  Find the named CSS colour that exactly or most closely matches a hex code, using straight-line distance in RGB space across the 148 named CSS colours. Source: https://hopi.co.uk/colour-name-finder/

  Parameters:

  • hex (required) — string — Hex colour code, e.g. #DC143C or #F00

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_colour_palette_generator read-only

  Generate a five-swatch colour palette from a base hex colour using a chosen scheme: analogous, complementary, triadic or mixed. Supporting swatches carry a small random variation, so results vary slightly each call. Source: https://hopi.co.uk/colour-palette-generator/

  Parameters:

  • hex (required) — string — Base colour as a six-digit hex code, e.g. #1F8A70
  • scheme — string — Colour scheme (default analogous)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_colour_picker read-only

  Given a six-digit hex colour code (with or without a leading #), return its hex, RGB and HSL values. Source: https://hopi.co.uk/colour-picker/

  Parameters:

  • hex (required) — string — Six-digit hex colour code, e.g. #1F8A70

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_colour_shades_generator read-only

  From a base hex colour, generate five progressively lighter tints (mixed towards white) and five progressively darker shades (mixed towards black), each in five equal steps of one sixth. Source: https://hopi.co.uk/colour-shades-generator/

  Parameters:

  • hex (required) — string — Base colour as a six-digit hex code, e.g. #1F8A70

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_combination_generator read-only

  List every way to choose r items from a list, ignoring order (combinations). Returns the total count and the combinations themselves (the first 5000). Source: https://hopi.co.uk/combination-generator/

  Parameters:

  • items (required) — array — The list of items to choose from
  • choose (required) — integer — How many items to pick in each combination (r)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_compound_interest_calculator read-only

  Project savings growth from a starting deposit plus a regular monthly contribution, compounded monthly with contributions added at the end of each month. Returns the final balance, total paid in and interest earned. Amounts in GBP, rate is the annual rate as a percentage. Source: https://hopi.co.uk/compound-interest-calculator/

  Parameters:

  • rate (required) — number — Annual interest rate as a percentage
  • years (required) — number — Term in years (1 to 100)
  • monthly — number — Monthly contribution in GBP (default 0)
  • principal — number — Starting deposit in GBP (default 0)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_contrast_checker read-only

  Work out the WCAG contrast ratio between a foreground (text) colour and a background colour, both as hex codes, and report whether it passes AA and AAA for normal and large text. Source: https://hopi.co.uk/contrast-checker/

  Parameters:

  • foreground (required) — string — Text colour as a six-digit hex code, e.g. #767676
  • background (required) — string — Background colour as a six-digit hex code, e.g. #FFFFFF

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_cron_expression_parser read-only

  Translate a standard five-field cron expression (minute, hour, day-of-month, month, day-of-week) into plain English. Understands stars, steps, ranges, lists and month and day names, plus shortcuts like @daily and @hourly. Source: https://hopi.co.uk/cron-expression-parser/

  Parameters:

  • expression (required) — string — A five-field cron expression, for example '*/5 9-17 * * MON-FRI', or a shortcut like @daily

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_crypto_profit_calculator read-only

  Work out profit or loss on a crypto trade from buy price, quantity and an optional per-side fee percentage. Returns breakeven price always, and profit, return percentage and total fees once a sell price is given. All figures are treated as GBP. Source: https://hopi.co.uk/crypto-profit-calculator/

  Parameters:

  • buy (required) — number — Buy price per unit
  • quantity (required) — number — Quantity of coin traded
  • fee — number — Fee percentage charged on each side (default 0, must be 0 to under 100)
  • sell — number — Sell price per unit (optional; omit to see breakeven only)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_css_gradient_generator read-only

  Build a ready-to-use CSS gradient from two colours. Choose a linear gradient with an angle in degrees, or a radial gradient. Returns the gradient value and a full background declaration. Source: https://hopi.co.uk/css-gradient-generator/

  Parameters:

  • colour1 (required) — string — First colour, e.g. #FF512F
  • colour2 (required) — string — Second colour, e.g. #DD2476
  • type — string — Gradient type (default linear)
  • angle — number — Angle in degrees for a linear gradient (default 90)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_css_minifier read-only

  Minify CSS by removing comments and needless whitespace, while preserving quoted strings and the spaces inside calc() expressions. Returns the minified CSS with before and after byte sizes. Source: https://hopi.co.uk/css-minifier/

  Parameters:

  • css (required) — string — The CSS source to minify

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_csv_to_json read-only

  Convert CSV text into a JSON array, following standard CSV quoting rules for embedded commas, quotes and line breaks. With headers on, the first row becomes object keys; with headers off, each row is an array of strings. Source: https://hopi.co.uk/csv-to-json/

  Parameters:

  • csv (required) — string — The CSV text to convert
  • firstRowHeaders — boolean — When true, the first row supplies the object keys; when false, every row becomes a plain array of strings (default true)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_cups_to_grams read-only

  Convert US cups of a common baking ingredient to grams (approximate). Ingredients: flour (plain flour), caster (caster sugar), brown (packed brown sugar), butter, cocoa (cocoa powder), oats, rice (uncooked rice), icing (icing sugar). Source: https://hopi.co.uk/cups-to-grams/

  Parameters:

  • cups (required) — number — Number of US cups
  • ingredient (required) — string — The ingredient

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_currency_converter read-only

  Convert an amount of money from one currency to another using Hopi's live mid-market exchange rates (updated hourly, 150+ currencies). Use ISO 4217 codes such as GBP, EUR, USD, JPY. Source: https://hopi.co.uk/currency-converter/

  Parameters:

  • amount (required) — number — The amount to convert
  • from (required) — string — Currency to convert from, ISO 4217 code e.g. GBP
  • to (required) — string — Currency to convert to, ISO 4217 code e.g. EUR

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_data_size_converter read-only

  Convert a digital storage size between units. Units: B (bytes), KB, MB, GB, TB. By default 1 KB = 1000 bytes (decimal, as storage is sold). Set binary to true for 1 KB = 1024 bytes (as Windows reports drive sizes). Source: https://hopi.co.uk/data-size-converter/

  Parameters:

  • value (required) — number — The size value to convert
  • from (required) — string — Unit to convert from
  • to (required) — string — Unit to convert to
  • binary — boolean — Use binary units (1 KB = 1024 bytes) instead of decimal (default false)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_date_calculator read-only

  Add or subtract a number of days, weeks, months or years from a date. Dates use the YYYY-MM-DD format. Months and years are clamped to the last day of the target month where needed. Returns the resulting date. Source: https://hopi.co.uk/date-calculator/

  Parameters:

  • date (required) — string — Start date in YYYY-MM-DD format
  • amount (required) — integer — How many units to move (0 to 100000)
  • unit — string — Unit to move by (default 'days')
  • direction — string — 'add' to move forwards, 'subtract' to move backwards (default 'add')

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_day_of_week_calculator read-only

  Find which day of the week a given date falls on. Dates use the YYYY-MM-DD format. Also reports which weekday that same day and month falls on in the current year. Source: https://hopi.co.uk/day-of-week-calculator/

  Parameters:

  • date (required) — string — The date in YYYY-MM-DD format

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_day_rate_calculator read-only

  Convert between a contractor day rate and an annual salary equivalent using a chosen number of billable working days per year (default 220). Mode 'to_salary' turns a day rate into yearly, monthly and weekly figures; mode 'to_rate' turns a salary into a day rate. Gross amounts in GBP, before tax. Source: https://hopi.co.uk/day-rate-calculator/

  Parameters:

  • mode (required) — string — 'to_salary' from a day rate, or 'to_rate' from a salary
  • salary — number — Annual salary in GBP (required for to_rate)
  • dayRate — number — Day rate in GBP (required for to_salary)
  • workingDays — number — Billable working days per year, 1 to 365 (default 220)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_days_between_dates read-only

  Count the number of days between two dates, with the total also shown in weeks and in weekdays (Monday to Friday). Dates use the YYYY-MM-DD format. Set inclusive to true to count both end days. Source: https://hopi.co.uk/days-between-dates/

  Parameters:

  • from (required) — string — Start date in YYYY-MM-DD format
  • to (required) — string — End date in YYYY-MM-DD format
  • inclusive — boolean — Count both end days rather than excluding the end day (default false)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_days_until_christmas read-only

  Count the number of sleeps until the next Christmas Day (25 December). Uses today's date by default, or an optional 'from' date in YYYY-MM-DD format. Source: https://hopi.co.uk/days-until-christmas/

  Parameters:

  • from — string — Optional date to count from, in YYYY-MM-DD format (defaults to today)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_dca_calculator read-only

  Work out the average cost basis across a series of pound-cost-averaged buys. Each buy is an amount of money spent and the price paid per unit. Returns total invested, coins acquired and average cost, plus current value and unrealised profit or loss if a current price is given. Figures are treated as GBP. Source: https://hopi.co.uk/dca-calculator/

  Parameters:

  • buys (required) — array — The list of buys
  • currentPrice — number — Current price per unit (optional), to value the position now

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_dice_roller read-only

  Roll one or more dice with a given number of sides. Returns each die result plus the total, highest and lowest. Source: https://hopi.co.uk/dice-roller/

  Parameters:

  • sides — integer — Number of sides on each die (default 6)
  • quantity — integer — How many dice to roll, 1 to 20 (default 1)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_diff_checker read-only

  Compare two texts line by line using a longest common subsequence diff, and report which lines were added and which were removed. An edited line shows as one removed line plus one added line. Comparison is exact, including spaces and case. Source: https://hopi.co.uk/diff-checker/

  Parameters:

  • a (required) — string — The original (left) text
  • b (required) — string — The changed (right) text

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_discount_calculator read-only

  Work out a discount and sale price. Mode 'pct': a percentage off a price. Mode 'fixed': a fixed pound amount off a price. Mode 'find': the discount percentage from an original price and a final price. All money figures are in pounds. Source: https://hopi.co.uk/discount-calculator/

  Parameters:

  • mode (required) — string — 'pct' percentage off, 'fixed' pound amount off, or 'find' the discount from two prices
  • price (required) — number — The original price (used in all modes)
  • amountOff — number — Fixed pound amount off (mode 'fixed' only)
  • finalPrice — number — The final price paid (mode 'find' only)
  • percentOff — number — Discount percentage (mode 'pct' only)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_dog_age_calculator read-only

  Convert a dog's age in years to an approximate human age, using the standard veterinary chart. The later rate depends on the dog's size: small, medium or large. Returns the human-equivalent age. Source: https://hopi.co.uk/dog-age-calculator/

  Parameters:

  • dogAge (required) — number — The dog's age in years (0 to 30)
  • size — string — Dog size band (default 'medium')

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_download_time_calculator read-only

  Estimate how long a download takes. Give a file size with its unit (MB, GB, TB) and a connection speed with its unit (Mbps or Gbps in bits per second, or MBps in bytes per second). Returns a human-readable duration and the time in seconds. Source: https://hopi.co.uk/download-time-calculator/

  Parameters:

  • size (required) — number — File size value
  • sizeUnit (required) — string — File size unit
  • speed (required) — number — Connection speed value
  • speedUnit (required) — string — Speed unit: Mbps/Gbps are bits per second, MBps is megabytes per second

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_due_date_calculator read-only

  Estimate a pregnancy due date from the first day of the last menstrual period (LMP) and cycle length. Method: adjust the LMP by (cycle - 28) days, then add 280 days for the due date. Also returns the dates the second and third trimesters begin (LMP-adjusted + 84 and + 182 days). Dates are ISO 'YYYY-MM-DD'. Source: https://hopi.co.uk/due-date-calculator/

  Parameters:

  • lmp (required) — string — First day of the last menstrual period, ISO date 'YYYY-MM-DD'
  • cycleLength — integer — Cycle length in days, 20 to 45 (default 28)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_dummy_data_generator read-only

  Generate fake but safe UK test records. Phone numbers come from Ofcom's reserved drama ranges and emails use RFC 2606 example domains, so no record can reach a real person. Returns an array of records, plus CSV text. Source: https://hopi.co.uk/dummy-data-generator/

  Parameters:

  • count (required) — integer — How many records to generate, from 1 to 1000
  • fields — array — Which fields to include (default all). Choose from firstName, lastName, fullName, email, ukMobile, ukLandline, streetAddress, town, postcode, dateOfBirth, company

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_email_header_analyser read-only

  Analyse raw email headers (the full source from Show original or View message source) without any network call: lists every Received hop in delivery order with host, IP, time and delay between hops; extracts From, Reply-To, Return-Path, Subject, Date, Message-ID and mailer; reads SPF, DKIM and DMARC results from Authentication-Results, ARC-Authentication-Results and Received-SPF with the domain each was checked for; and flags warning signs such as Reply-To on a different domain, SPF or DMARC failure, no DKIM, a display name that pretends to be an address or brand, a first hop from a home connection, clock skew and a mismatched Message-ID domain. Returns a verdict (consistent, caution or suspicious). It does not query DNS, so it reports what the receiving servers recorded rather than re-checking it. Source: https://hopi.co.uk/email-header-analyser/

  Parameters:

  • headers (required) — string — The raw message headers, pasted as text

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_email_link_generator read-only

  Build a correctly percent-encoded mailto link from to, cc, bcc, subject and body fields, plus a ready to paste HTML anchor snippet. Spaces are encoded as %20 and line breaks as %0D%0A, as the mailto standard expects. Source: https://hopi.co.uk/email-link-generator/

  Parameters:

  • to (required) — string — One or more recipient addresses, separated by commas or semicolons
  • cc — string — Optional cc addresses, separated by commas or semicolons
  • bcc — string — Optional bcc addresses, separated by commas or semicolons
  • body — string — Optional body text; line breaks are preserved
  • subject — string — Optional subject line
  • linkText — string — Optional visible text for the HTML anchor (default 'Email us')

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_emoji_remover read-only

  Remove emoji from a block of text, leaving the words and normal punctuation intact. Joined emoji sequences (such as a family or a flag) count as a single emoji. The copyright, registered and trademark symbols are kept. Returns the cleaned text and how many emoji were removed. Source: https://hopi.co.uk/emoji-remover/

  Parameters:

  • text (required) — string — The text to clean

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_energy_cost_calculator read-only

  Work out the running cost of an electrical appliance from its power in watts, hours used per day and your electricity unit price in pence per kWh. Returns daily, weekly, monthly and yearly cost plus kWh used. Costs in GBP. Source: https://hopi.co.uk/energy-cost-calculator/

  Parameters:

  • watts (required) — number — Appliance power draw in watts (0 to 100000)
  • hoursPerDay (required) — number — Hours used per day (0 to 24)
  • pencePerKwh (required) — number — Electricity unit price in pence per kWh

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_env_to_json read-only

  Convert between a .env file and a JSON object. In env-to-json mode, each line is split on its first equals sign into a key and value, blank and commented lines are skipped, a leading export is removed, and matching surrounding quotes are stripped (double-quoted values also unescape \n); duplicate keys keep the last value. In json-to-env mode, a JSON object becomes KEY=value lines, quoting values that contain spaces, a hash or a newline. Source: https://hopi.co.uk/env-to-json/

  Parameters:

  • text (required) — string — The .env file text, or the JSON object text, depending on mode
  • mode — string — 'env-to-json' parses a .env file into JSON, 'json-to-env' turns a JSON object into .env lines (default env-to-json)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_eth_address_checksum read-only

  Validate an Ethereum address's EIP-55 capitalisation checksum and return the correctly checksummed form. Reports whether the input is already checksummed, lacks a checksum (all one case), or fails the checksum. Uses keccak-256 exactly as EIP-55 specifies. Source: https://hopi.co.uk/eth-address-checksum/

  Parameters:

  • address (required) — string — The Ethereum address, with or without a 0x prefix

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_eth_unit_converter read-only

  Convert an amount given in wei, gwei or ETH into all three units, using exact 18-decimal integer maths (no floating point error). 1 ETH is 1e18 wei; 1 gwei is 1e9 wei. Source: https://hopi.co.uk/eth-unit-converter/

  Parameters:

  • amount (required) — string — The amount to convert, as a plain number (string preferred to keep full precision), e.g. "1.5"
  • unit (required) — string — The unit the amount is given in

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_euromillions_generator read-only

  Generate random EuroMillions lines. Each line has 5 main numbers from 1 to 50 and 2 Lucky Stars from 1 to 12. Source: https://hopi.co.uk/euromillions-generator/

  Parameters:

  • lines — integer — How many lines to generate, 1 to 10 (default 1)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_event_wine_calculator read-only

  Work out how many bottles of red, white and Champagne to buy for an event, from the number of guests and glasses per guest. Ticking different wines splits a colour into one wine per glass, each poured once for every guest. Source: https://hopi.co.uk/event-wine-calculator/

  Parameters:

  • guests (required) — number — Number of guests
  • redSize — number — Red glass size in ml: 125, 175 or 250
  • whiteSize — number — White glass size in ml: 125, 175 or 250
  • redGlasses — number — Glasses of red per guest
  • redDifferent — boolean — Serve a different red for each glass
  • whiteGlasses — number — Glasses of white per guest
  • sparklingSize — number — Sparkling glass size in ml: 100, 125 or 150
  • whiteDifferent — boolean — Serve a different white for each glass
  • sparklingGlasses — number — Glasses of Champagne or sparkling per guest
  • sparklingDifferent — boolean — Serve a different sparkling for each glass

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_fortune_cookie read-only

  Crack open a virtual fortune cookie and receive a random cheerful fortune. Returns the fortune. Source: https://hopi.co.uk/fortune-cookie/

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_fraction_calculator read-only

  Add, subtract, multiply or divide two fractions, giving the simplified result, a mixed number where relevant, and the decimal value. Each fraction is a numerator over a denominator, all whole numbers (numerators may be negative). Source: https://hopi.co.uk/fraction-calculator/

  Parameters:

  • op (required) — string — Operation: add, sub (subtract), mul (multiply) or div (divide)
  • n1 (required) — integer — First numerator
  • d1 (required) — integer — First denominator (not zero)
  • n2 (required) — integer — Second numerator
  • d2 (required) — integer — Second denominator (not zero)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_fraction_to_decimal read-only

  Convert between fractions and decimals. Mode 'toDecimal': give a numerator and denominator (whole numbers) to get the decimal and percentage. Mode 'toFraction': give a decimal to get the closest simplified fraction (denominator up to 10,000), noting whether it is exact. Source: https://hopi.co.uk/fraction-to-decimal/

  Parameters:

  • mode (required) — string — 'toDecimal' from a fraction, or 'toFraction' from a decimal
  • decimal — number — The decimal to convert (mode 'toFraction')
  • numerator — integer — Numerator (mode 'toDecimal')
  • denominator — integer — Denominator, not zero (mode 'toDecimal')

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_fuel_cost_calculator read-only

  Estimate the fuel cost of a journey from the distance in miles, the car's fuel economy in miles per gallon (UK gallon) and the pump price in pence per litre. Optionally double it for a return trip and split between passengers. Returns total cost, litres used and cost per person. Costs in GBP. Source: https://hopi.co.uk/fuel-cost-calculator/

  Parameters:

  • miles (required) — number — One-way distance in miles
  • mpg (required) — number — Fuel economy in miles per UK gallon
  • pencePerLitre (required) — number — Pump price in pence per litre
  • people — integer — Number of people to split the cost between (default 1)
  • returnTrip — boolean — Double the distance for a return journey (default false)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_hash_generator read-only

  Compute the SHA-256, SHA-1 or SHA-512 hash of a piece of text and return the hex digest. Uses WebCrypto on Hopi's server. SHA-1 is included for compatibility with older systems only and should not be used for anything new. Source: https://hopi.co.uk/hash-generator/

  Parameters:

  • text (required) — string — The text to hash
  • algorithm — string — Hash algorithm (default SHA-256)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_hash_identifier read-only

  Identify the most likely algorithms behind a hash string from its length, character set and any prefix. Covers MD5, NTLM, MD4, SHA-1, RIPEMD-160, SHA-224/256/384/512, the SHA3 family, CRC32, bcrypt, Argon2, sha512crypt, sha256crypt and md5crypt, plus Base64 length hints. A hash does not carry its algorithm, so results are ranked best guesses, not proof. Source: https://hopi.co.uk/hash-identifier/

  Parameters:

  • hash (required) — string — The hash string to identify

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_heart_rate_zones read-only

  Estimate maximum heart rate and five training zones (bpm) from age. Max HR = 220 - age. Method 'max' uses percentages of max HR (50-60, 60-70, 70-80, 80-90, 90-100%). Method 'karvonen' uses heart rate reserve and needs restingHeartRate: zone = (maxHR - resting) x intensity + resting. Source: https://hopi.co.uk/heart-rate-zones/

  Parameters:

  • age (required) — number — Age in years
  • method — string — 'max' (percentage of max HR) or 'karvonen' (heart rate reserve). Default 'max'
  • restingHeartRate — number — Resting heart rate in bpm, required for the Karvonen method

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_hex_to_rgb read-only

  Convert a hex colour code (3, 6 or 8 digits, with or without a leading #) to its RGB and HSL values. Source: https://hopi.co.uk/hex-to-rgb/

  Parameters:

  • hex (required) — string — Hex colour code, e.g. #D7263D or F0C

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_hidden_character_checker read-only

  Scan text for hidden and suspicious Unicode characters and return a cleaned copy. Finds zero-width space, joiner and non-joiner (U+200B to U+200D), word joiner U+2060, byte order mark U+FEFF, soft hyphen U+00AD, no-break and narrow no-break spaces, hair and thin spaces, bidirectional controls (U+202A to U+202E, U+2066 to U+2069), variation selectors, Unicode tag characters U+E0000 to U+E007F (the invisible prompt-injection carrier, decoded to readable text in tagText), control characters, every other default-ignorable or format character (for example the Khmer inherent vowels U+17B4 and U+17B5 used to pad AI text), and Latin words containing Cyrillic or Greek lookalike letters. Curly quotes and dashes are reported separately as stylistic, not hidden. The cleaned text removes the invisible characters, turns special spaces into ordinary spaces and keeps zero-width joiners and selectors that form emoji. It cannot detect statistical AI watermarks such as SynthID-Text, which live in word choice. Source: https://hopi.co.uk/hidden-character-checker/

  Parameters:

  • text (required) — string — The text to scan
  • plainPunctuation — boolean — Also flatten curly quotes, en and em dashes and ellipses to plain ASCII in the cleaned text

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_holiday_entitlement_calculator read-only

  Work out UK statutory paid holiday entitlement from the number of days worked per week, using 5.6 weeks a year capped at the statutory 28 days. Optionally scale to a part-year by the number of months worked. Returns entitlement in days and weeks. Source: https://hopi.co.uk/holiday-entitlement-calculator/

  Parameters:

  • daysPerWeek (required) — number — Days worked per week (1 to 7)
  • months — number — Months of the year worked (1 to 12, default 12)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_hourly_to_salary read-only

  Convert between an hourly pay rate and an annual salary based on hours worked per week (52 weeks a year). Mode 'to_salary' turns an hourly rate into annual, monthly and weekly pay; mode 'to_hourly' turns a salary into an hourly rate. Gross amounts in GBP, before tax. Source: https://hopi.co.uk/hourly-to-salary/

  Parameters:

  • mode (required) — string — 'to_salary' from an hourly rate, or 'to_hourly' from a salary
  • hoursPerWeek (required) — number — Hours worked per week (greater than 0, up to 168)
  • salary — number — Annual salary in GBP (required for to_hourly)
  • hourlyRate — number — Hourly pay rate in GBP (required for to_salary)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_hours_calculator read-only

  Work out the hours worked between a start time and an end time, minus an optional unpaid break. Times use 24-hour HH:MM format. Handles overnight shifts where the end time is earlier than the start. Returns the worked time as hours and minutes and as decimal hours. Source: https://hopi.co.uk/hours-calculator/

  Parameters:

  • start (required) — string — Start time in 24-hour HH:MM format, e.g. 09:00
  • end (required) — string — End time in 24-hour HH:MM format, e.g. 17:30
  • breakMinutes — number — Unpaid break in minutes (default 0)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_hsl_converter read-only

  Convert a hex colour code to hue, saturation and lightness (HSL), or convert HSL values to hex and RGB. Source: https://hopi.co.uk/hsl-converter/

  Parameters:

  • mode (required) — string — Direction of conversion
  • h — number — Hue 0 to 360 (for hsl_to_hex)
  • l — number — Lightness 0 to 100 (for hsl_to_hex)
  • s — number — Saturation 0 to 100 (for hsl_to_hex)
  • hex — string — Hex colour code, e.g. #1FE85C (for hex_to_hsl)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_html_escape read-only

  Escape the five special HTML characters (& < > " ') into entities so text is safe to place in HTML, or unescape named and numeric HTML entities back into plain characters. Source: https://hopi.co.uk/html-escape/

  Parameters:

  • text (required) — string — The text to escape, or the HTML with entities to unescape
  • mode (required) — string — 'escape' text to entities, or 'unescape' entities back to text

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_http_status_codes read-only

  Look up a standard HTTP status code by number and get its name, meaning and class (1xx to 5xx), or search all standard codes by a word in the number, name or description. Source: https://hopi.co.uk/http-status-codes/

  Parameters:

  • code — integer — An HTTP status code to look up, for example 404
  • query — string — A word to search for across code numbers, names and descriptions

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_iban_validator read-only

  Validate an IBAN or generate a test IBAN. Pass 'iban' to check it: the tool normalises it (uppercase, no spaces), confirms the length matches the country's published length, and runs the mod-97 checksum (move the first four characters to the end, map letters to numbers A=10 to Z=35, valid when the number mod 97 is 1). Pass 'country' (a two-letter ISO code) to generate a structurally valid TEST IBAN with a random bank and account portion and correct check digits. Generated IBANs are test values only and are not tied to any real account. All processing is local; nothing is stored. Source: https://hopi.co.uk/iban-validator/

  Parameters:

  • iban — string — An IBAN to validate (spaces and case are ignored)
  • country — string — A two-letter country code (e.g. GB, DE, FR) to generate a test IBAN for instead of validating

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_ics_generator read-only

  Build a .ics (iCalendar, RFC 5545) calendar file for a single event and return the file text. Give a title, startDate and endDate as 'YYYY-MM-DD'. For timed events give startTime and endTime as 'HH:MM' (24-hour, read in the caller's local time zone and stored as UTC); set allDay true for an all-day event instead. Location and description are optional. Returns the .ics text ready to save. Source: https://hopi.co.uk/ics-generator/

  Parameters:

  • title (required) — string — Event title (SUMMARY)
  • startDate (required) — string — Start date, ISO 'YYYY-MM-DD'
  • allDay — boolean — True for an all-day event (no times). Default false
  • endDate — string — End date, ISO 'YYYY-MM-DD'. Defaults to startDate
  • endTime — string — End time 'HH:MM' 24-hour, timed events only. Defaults to startTime
  • location — string — Optional location
  • startTime — string — Start time 'HH:MM' 24-hour, timed events only. Default '00:00'
  • description — string — Optional description

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_inflation_calculator read-only

  Adjust a money amount for UK inflation. Mode 'cpi' uses the ONS monthly CPI index (2015 = 100) between two months from January 1988 to August 2026 and returns the adjusted value, total change and average annual rate. Mode 'custom' compounds a chosen annual rate over a number of years. Amounts in GBP. Source: https://hopi.co.uk/inflation-calculator/

  Parameters:

  • mode (required) — string — 'cpi' uses the ONS CPI index between two months; 'custom' uses your own rate
  • amount (required) — number — The money amount to adjust
  • years — number — Custom mode: number of years (0 to 200)
  • toYear — integer — CPI mode: ending year (default is the latest year)
  • toMonth — integer — CPI mode: ending month (1 to 12, default is the latest month)
  • fromYear — integer — CPI mode: starting year (1988 to 2026)
  • fromMonth — integer — CPI mode: starting month (1 to 12)
  • ratePercent — number — Custom mode: annual inflation rate as a percentage (-50 to 100)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_json_formatter read-only

  Pretty print, minify or validate JSON. Formatting and minifying only change whitespace; key order, values and structure stay exactly as they were. Returns the output text or a clear parse error. Source: https://hopi.co.uk/json-formatter/

  Parameters:

  • json (required) — string — The JSON text to process
  • mode — string — 'format' to pretty print, 'minify' to strip whitespace, 'validate' to only check validity (default format)
  • indent — integer — Number of spaces per indent level when formatting (default 2)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_json_to_csv read-only

  Convert a JSON array of objects into CSV. The union of all keys becomes the header row in first-seen order, missing keys become empty cells, and nested objects or arrays are written back as compact JSON in the cell. Output follows RFC 4180 quoting. Source: https://hopi.co.uk/json-to-csv/

  Parameters:

  • json (required) — string — A JSON array of objects to convert

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_json_to_typescript read-only

  Convert a JSON sample into TypeScript interfaces and types. Objects become named interfaces (PascalCase from their key), nested objects get their own interfaces, arrays become element-type arrays with keys merged across all elements (keys missing from some elements are marked optional), and null values are folded into unions such as string | null. Empty arrays become unknown[] and empty objects become Record<string, unknown>. Runs on Hopi's server; nothing is stored. Source: https://hopi.co.uk/json-to-typescript/

  Parameters:

  • json (required) — string — A JSON sample to convert. It may be an object, an array or a primitive value.
  • rootName — string — Name for the root interface or type alias (default Root).

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_json_yaml_converter read-only

  Convert data between JSON and YAML in both directions. JSON to YAML parses with JSON.parse and serialises with js-yaml at two-space indent; YAML to JSON parses with js-yaml and prints with JSON.stringify. Runs on Hopi's server; nothing is stored. Source: https://hopi.co.uk/json-yaml-converter/

  Parameters:

  • text (required) — string — The JSON or YAML text to convert
  • mode — string — Direction of conversion (default json-to-yaml)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_jwt_decoder read-only

  Decode a JSON Web Token's header and payload from base64url. The signature is never verified, so a decoded claim proves nothing on its own. Reports the algorithm, the exp, iat and nbf time claims, and whether the token is expired. A leading Bearer prefix and whitespace are handled. Source: https://hopi.co.uk/jwt-decoder/

  Parameters:

  • token (required) — string — The JWT to decode, optionally with a leading 'Bearer ' prefix

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_kg_to_lbs read-only

  Convert a weight in kilograms to pounds (avoirdupois lb), with the answer also split into whole pounds and ounces. Uses exactly 0.45359237 kg per pound and 16 ounces per pound. Source: https://hopi.co.uk/kg-to-lbs/

  Parameters:

  • kilograms (required) — number — Weight in kilograms

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_kg_to_stone read-only

  Convert a weight in kilograms to UK stone and pounds. Returns whole stone plus remaining pounds, and the totals in pounds and decimal stone. Source: https://hopi.co.uk/kg-to-stone/

  Parameters:

  • kilograms (required) — number — Weight in kilograms

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_lbs_to_kg read-only

  Convert a weight in pounds (avoirdupois lb) to kilograms and grams, with the UK stones-and-pounds form alongside. Uses exactly 0.45359237 kg per pound and 14 pounds per stone. Source: https://hopi.co.uk/lbs-to-kg/

  Parameters:

  • pounds (required) — number — Weight in pounds (decimals allowed, e.g. 7.5 for 7 lb 8 oz)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_leak_tracer read-only

  Watermark a document per recipient and trace a leaked copy. Mode 'mark' takes text and a list of recipient names (up to 255) and returns one copy per recipient carrying that recipient's number as an 18-character invisible marker (U+2060 frame, 8-bit number plus 8-bit check written in U+200B and U+200C) after the first word and every twentieth word, plus a tracer key that stores the list; set spacing to also encode the pattern in no-break spaces. Mode 'trace' takes a leaked copy plus the same recipients or the key and returns the recipient, the copy number, how many markers were found and agreed, and a confidence level. Marks survive copy and paste but not retyping, screenshots, OCR or a hidden-character cleaner. Source: https://hopi.co.uk/leak-tracer/

  Parameters:

  • mode (required) — string — mark or trace
  • text (required) — string — Mark: the document. Trace: the leaked copy or fragment
  • key — string — Trace: the tracer key returned by mark, instead of recipients
  • spacing — boolean — Mark: also encode the pattern as no-break spaces
  • recipients — array — Recipient names in order (mark: required; trace: this or key)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_leap_year_checker read-only

  Check whether a year is a leap year, applying the divisible-by-4, century, and divisible-by-400 rules. Returns the verdict, the divisibility tests, and the next and previous leap years. Source: https://hopi.co.uk/leap-year-checker/

  Parameters:

  • year (required) — integer — The year to check (1 to 9999)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_length_converter read-only

  Convert a length from one unit to another. Units: mm, cm, m, km, in (inches), ft (feet), yd (yards), mi (miles). Source: https://hopi.co.uk/length-converter/

  Parameters:

  • value (required) — number — The length value to convert
  • from (required) — string — Unit to convert from
  • to (required) — string — Unit to convert to

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_link_cleaner read-only

  Clean and inspect a URL without visiting it: strips tracking parameters (utm_*, fbclid, gclid, msclkid, mc_eid, _hsenc and many more, grouped by network), unwraps redirect wrappers whose destination is in the address itself (Outlook Safe Links, Proofpoint URL Defense v2 and v3, Google /url?q=, Facebook l.php, YouTube, LinkedIn, Reddit, Slack, Tumblr) and checks the address for phishing signs: punycode and mixed-script hosts, brand names in subdomains, embedded user:pass@, IP hosts, data: and javascript: schemes, risky TLDs, link shorteners, double encoding and overlong paths. Returns the clean link, what was removed, the real registrable domain, a list of warnings and a verdict (clean, caution or avoid). It cannot know where a shortener goes or whether a site is malicious; no DNS or HTTP requests are made. Source: https://hopi.co.uk/link-cleaner/

  Parameters:

  • url (required) — string — The link to clean and inspect

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_litres_to_pints read-only

  Convert between litres and pints. Direction 'litres-to-pints' takes litres and returns UK pints, US pints and millilitres. Direction 'pints-to-litres' takes UK pints and returns litres. Source: https://hopi.co.uk/litres-to-pints/

  Parameters:

  • value (required) — number — The value to convert (litres or UK pints depending on direction)
  • direction (required) — string — Which way to convert

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_loan_calculator read-only

  Work out the monthly repayment on a loan from the amount borrowed, the annual interest rate and the term in years, using the standard amortising formula. Returns the monthly payment, total repaid and total interest. Amounts in GBP. Source: https://hopi.co.uk/loan-calculator/

  Parameters:

  • amount (required) — number — Amount borrowed in GBP (greater than zero)
  • rate (required) — number — Annual interest rate (APR) as a percentage (0 to 100)
  • years (required) — number — Loan term in years (greater than 0, up to 30)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_lookalike_domain_generator read-only

  Generate the lookalike variants of a domain that could be used to impersonate it, grouped by technique, as a defensive typosquat check. Techniques: omission (missing character), repetition (doubled character), transposition (swapped adjacent), keyboard (QWERTY neighbour), vowel (vowel swap), homoglyph (ASCII lookalikes such as rn for m, vv for w, cl for d, 0 for o, 1 for l), confusable (Cyrillic or Greek letters, shown with the xn-- punycode form), hyphenation, subdomain (prefix and subdomain tricks using the reserved .example ending), and tld (different endings such as .com, .co.uk, .uk, .org, .net, .io, .app, .co). Two-part endings like co.uk are recognised. Each variant carries its punycode (IDNA ASCII) form. The list is deduplicated and capped at 500. No availability, DNS or WHOIS check is made; it only says what could be registered, not what is. Source: https://hopi.co.uk/lookalike-domain-generator/

  Parameters:

  • domain (required) — string — The domain to check, e.g. example.co.uk
  • techniques — array — Optional subset of techniques to use; omit for all

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_lorem_ipsum_generator read-only

  Generate lorem ipsum placeholder text. Choose whether the count is a number of paragraphs, sentences or words, and how many. Limits are 100 paragraphs, 500 sentences or 2000 words. Source: https://hopi.co.uk/lorem-ipsum-generator/

  Parameters:

  • count (required) — integer — How many paragraphs, sentences or words to produce
  • mode — string — What the count refers to (default paragraphs)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_lottery_number_generator read-only

  Generate random lines for a UK lottery game: Lotto (6 numbers from 1 to 59), Thunderball (5 from 1 to 39 plus a Thunderball from 1 to 14) or Set For Life (5 from 1 to 47 plus a Life Ball from 1 to 10). Source: https://hopi.co.uk/lottery-number-generator/

  Parameters:

  • game — string — Which game to play (default lotto)
  • lines — integer — How many lines to generate, 1 to 10 (default 1)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_magic_8_ball read-only

  Ask the Magic 8 Ball a yes or no question and receive one of its twenty classic answers at random. Returns the answer. Source: https://hopi.co.uk/magic-8-ball/

  Parameters:

  • question — string — The yes or no question to ask (optional)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_margin_calculator read-only

  Work out profit, gross margin and markup from a cost price and a selling price. Margin is profit as a percentage of the selling price; markup is profit as a percentage of the cost. Amounts in GBP. Source: https://hopi.co.uk/margin-calculator/

  Parameters:

  • cost (required) — number — Cost price in GBP
  • price (required) — number — Selling price in GBP

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_markdown_previewer read-only

  Render a small, safe subset of markdown to HTML: headings (# to ###), bold, italic, links (http, https or mailto only), inline code, fenced code blocks, bulleted and numbered lists, and blockquotes. Every character is HTML-escaped first, so raw HTML is shown as text and never executed. Source: https://hopi.co.uk/markdown-previewer/

  Parameters:

  • markdown (required) — string — The markdown source to render

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_market_cap_calculator read-only

  Calculate a coin's market cap (price times circulating supply) and fully diluted valuation, or work backwards to the price implied by a target market cap. Works in any currency; nothing is looked up. Source: https://hopi.co.uk/market-cap-calculator/

  Parameters:

  • mode (required) — string — market_cap: price times supply. implied_price: target cap divided by supply.
  • supply (required) — number — Circulating supply (for both modes)
  • price — number — Current price per coin (for market_cap)
  • target — number — Target market cap (for implied_price)
  • current — number — Current price per coin, to show the multiple (optional, implied_price mode)
  • maxSupply — number — Maximum or total supply for FDV (optional, market_cap mode)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_meta_tag_generator read-only

  Build a complete HTML head snippet from page details: title, meta description, canonical link, Open Graph and Twitter card tags. Returns the ready-to-paste snippet plus character counts. Source: https://hopi.co.uk/meta-tag-generator/

  Parameters:

  • title — string — Page title (guideline is around 60 characters)
  • ogType — string — Open Graph type (default 'website')
  • ogImage — string — Open Graph image URL
  • ogTitle — string — Open Graph title (defaults to title if omitted)
  • canonical — string — Canonical URL for the page
  • description — string — Meta description (guideline is around 155 characters)
  • twitterCard — string — Twitter card type (default 'summary_large_image')
  • ogDescription — string — Open Graph description (defaults to description if omitted)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_miles_to_km read-only

  Convert between miles and kilometres. Direction 'miles-to-km' takes miles and returns kilometres. Direction 'km-to-miles' takes kilometres and returns miles. Source: https://hopi.co.uk/miles-to-km/

  Parameters:

  • value (required) — number — The distance value to convert
  • direction (required) — string — Which way to convert

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_military_time_converter read-only

  Convert between 24-hour (military) time and 12-hour clock time. Direction '24h-to-12h' takes a 24-hour time like '1430' or '14:30'. Direction '12h-to-24h' takes a 12-hour time like '2:30' with a meridiem of am or pm (the meridiem can also be written in the time string). Source: https://hopi.co.uk/military-time-converter/

  Parameters:

  • time (required) — string — The time to convert, e.g. '1430', '14:30', '2:30 pm'
  • direction (required) — string — Which way to convert
  • meridiem — string — am or pm for 12h-to-24h when not in the time string (default pm)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_minutes_to_hours read-only

  Convert a number of minutes into hours and minutes, or convert hours (plus optional extra minutes) into total minutes. Set mode to 'minutesToHours' or 'hoursToMinutes'. Returns a clock-style breakdown and decimal hours. Source: https://hopi.co.uk/minutes-to-hours/

  Parameters:

  • mode (required) — string — Direction of the conversion
  • hours — number — Hours to convert (used when mode is 'hoursToMinutes', 0 to 100000)
  • minutes — number — Minutes to convert (used when mode is 'minutesToHours', 0 to 10000000)
  • extraMinutes — number — Extra minutes to add to the hours (used when mode is 'hoursToMinutes', default 0)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_moon_phase_calculator read-only

  Work out the moon phase for a date, based on the synodic month since a known new moon. Dates use the YYYY-MM-DD format and default to today. Returns the phase name, illuminated percentage, moon age in days, and the next full and new moons. Source: https://hopi.co.uk/moon-phase-calculator/

  Parameters:

  • date — string — Optional date in YYYY-MM-DD format (defaults to today)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_morse_code_translator read-only

  Translate text into international Morse code, or Morse code back into text. Letters are separated by spaces and words by a forward slash. When decoding, underscores are treated as dashes and pipes as word separators. Unknown Morse sequences appear as # in the output. Source: https://hopi.co.uk/morse-code-translator/

  Parameters:

  • text (required) — string — The text or Morse code to translate
  • direction — string — 't2m' text to Morse (default), 'm2t' Morse to text

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_mortgage_calculator read-only

  Work out the monthly payment on a repayment mortgage at a constant interest rate, using the standard amortising formula. Returns the monthly payment, total repaid and total interest. Fees and rate changes are not included. Amounts in GBP. Source: https://hopi.co.uk/mortgage-calculator/

  Parameters:

  • amount (required) — number — Amount borrowed in GBP (greater than zero)
  • rate (required) — number — Annual interest rate as a percentage (0 to 50)
  • years (required) — number — Mortgage term in years (greater than 0, up to 50)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_mortgage_overpayment_calculator read-only

  See how much time and interest a regular monthly overpayment saves on a repayment mortgage. Give the current balance, annual rate, remaining term in years and the extra amount paid each month. Returns the time saved, interest saved, new payoff time and the monthly payment. Amounts in GBP. Source: https://hopi.co.uk/mortgage-overpayment-calculator/

  Parameters:

  • balance (required) — number — Current mortgage balance in GBP (greater than zero)
  • rate (required) — number — Annual interest rate as a percentage (0 to 50)
  • years (required) — number — Remaining term in years (greater than 0, up to 50)
  • extra (required) — number — Extra monthly overpayment in GBP (0 or more)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_mpg_converter read-only

  Convert fuel economy between UK miles per gallon and litres per 100 km. Direction 'mpg-to-l100' takes UK mpg. Direction 'l100-to-mpg' takes litres per 100 km. Also returns US mpg, km per litre and miles per litre. Source: https://hopi.co.uk/mpg-converter/

  Parameters:

  • value (required) — number — The fuel economy value (UK mpg or L/100km depending on direction)
  • direction (required) — string — Which way to convert

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_national_insurance_calculator read-only

  Work out UK employee Class 1 National Insurance for the 2026/27 tax year from an annual gross salary. Uses the primary threshold of £12,570, upper earnings limit of £50,270, 8% between them and 2% above. Returns NI due per year, month and week plus the effective rate. Amounts in GBP. Source: https://hopi.co.uk/national-insurance-calculator/

  Parameters:

  • salary (required) — number — Annual gross salary in GBP

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_nato_phonetic_alphabet read-only

  Spell text out using the NATO phonetic alphabet (Alfa, Bravo, Charlie and so on), or convert a phonetic spelling back into plain text. Spaces become (space). When converting back, common variants such as Alpha, Juliet, Xray, Niner and Fife are accepted; unrecognised words appear as #. Source: https://hopi.co.uk/nato-phonetic-alphabet/

  Parameters:

  • text (required) — string — The text or phonetic spelling to convert
  • direction — string — 't2n' text to phonetic (default), 'n2t' phonetic to text

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_net_to_gross read-only

  Work out the gross salary needed to achieve a desired take-home (net) pay for the 2026/27 tax year in England, Wales and Northern Ireland, using code 1257L income tax bands with personal allowance taper and employee National Insurance. Give the net figure as yearly or monthly. Returns the required gross, tax and NI. Amounts in GBP. Source: https://hopi.co.uk/net-to-gross/

  Parameters:

  • net (required) — number — Desired take-home pay in GBP
  • period — string — Whether the net figure is yearly or monthly (default year)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_new_year_countdown read-only

  Count down to the next New Year (midnight at the start of 1 January): days, hours, minutes, seconds and sleeps remaining, plus the weekday New Year's Day falls on. Uses the current time by default, or an optional 'from' date (YYYY-MM-DD) or ISO date-time, in which case everything is worked out in UTC. Source: https://hopi.co.uk/new-year-countdown/

  Parameters:

  • from — string — Optional moment to count from: YYYY-MM-DD (taken as 00:00 UTC) or a full ISO 8601 date-time such as 2026-12-31T18:30:00Z. Defaults to now.

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_number_base_converter read-only

  Convert a whole number from one base to another between binary, octal, decimal and hexadecimal. Uses BigInt so values of any size convert exactly. Returns the value in the requested base plus all four bases. Source: https://hopi.co.uk/number-base-converter/

  Parameters:

  • value (required) — string — The number to convert, as text (optional 0b/0o/0x prefix, spaces and underscores ignored, may be negative)
  • fromBase (required) — string — The base the value is written in
  • toBase (required) — string — The base to convert to

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_number_to_words read-only

  Convert a number into written English words. Set currency to true to write it as UK pounds and pence (cheque style, ending 'only'). Supports up to 999,999,999,999 with decimals to two places. Source: https://hopi.co.uk/number-to-words/

  Parameters:

  • value (required) — string — The number to spell out, e.g. '1234.5' or '19.99'. May include commas.
  • currency — boolean — Write as UK pounds and pence (default false)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_oven_temperature_converter read-only

  Convert an oven temperature. Scale 'c' is conventional Celsius, 'fan' is fan/convection Celsius, 'f' is Fahrenheit, 'gas' is UK gas mark (1 to 9). Returns conventional Celsius, fan Celsius, Fahrenheit and the nearest gas mark. Source: https://hopi.co.uk/oven-temperature-converter/

  Parameters:

  • value (required) — number — The temperature value (or gas mark 1 to 9 when scale is 'gas')
  • scale (required) — string — The scale of the input value

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_overtime_pay_calculator read-only

  Work out gross overtime pay from a base hourly rate and hours worked at three multipliers: standard (1x), time and a half (1.5x) and double time (2x). At least one hours figure is required. Returns pay at each rate, the total and total hours. Gross pay in GBP, before tax and NI. Source: https://hopi.co.uk/overtime-pay-calculator/

  Parameters:

  • rate (required) — number — Base hourly rate in GBP
  • doubleHours — number — Hours paid at double time, 2x (default 0)
  • standardHours — number — Hours paid at the standard rate (default 0)
  • timeAndHalfHours — number — Hours paid at time and a half, 1.5x (default 0)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_password_strength_checker read-only

  Estimate how strong a password is: an entropy estimate in bits, a rough offline crack time (assuming ten billion guesses a second), a 0 to 4 score with a verdict, and warnings about weak patterns such as dictionary words, sequences and repeats. Source: https://hopi.co.uk/password-strength-checker/

  Parameters:

  • password (required) — string — The password to assess (never uploaded; assessed locally)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_percentage_calculator read-only

  Work out percentages three ways. Mode 'of': what is P percent of a number. Mode 'what': what percentage the part is of the whole. Mode 'change': the percentage change from a starting value to an end value. Source: https://hopi.co.uk/percentage-calculator/

  Parameters:

  • mode (required) — string — 'of' percent of a number, 'what' one number as a percentage of another, or 'change' percentage change
  • to — number — End value (mode 'change')
  • from — number — Starting value (mode 'change', not zero)
  • part — number — The part (mode 'what')
  • whole — number — The whole (mode 'what', not zero)
  • number — number — The number (mode 'of')
  • percent — number — The percentage (mode 'of')

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_percentage_change_calculator read-only

  Work out the percentage change from a starting value to an end value, using the starting value as the base. A positive result is an increase, a negative result is a decrease. Source: https://hopi.co.uk/percentage-change-calculator/

  Parameters:

  • from (required) — number — The starting value (not zero)
  • to (required) — number — The end value

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_percentage_decrease_calculator read-only

  Decrease a number by a percentage and see the new value and the amount taken off. For example, 250 decreased by 15 percent. Source: https://hopi.co.uk/percentage-decrease-calculator/

  Parameters:

  • number (required) — number — The starting number
  • percent (required) — number — The percentage to take off

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_percentage_difference_calculator read-only

  Work out the percentage difference between two values using the average-based formula: the absolute gap divided by the average of the two, times 100. The result is symmetric, so the order of the two values does not matter. Source: https://hopi.co.uk/percentage-difference-calculator/

  Parameters:

  • a (required) — number — The first value
  • b (required) — number — The second value

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_percentage_increase_calculator read-only

  Increase a number by a percentage and see the new value and the amount added. For example, 250 increased by 15 percent. Source: https://hopi.co.uk/percentage-increase-calculator/

  Parameters:

  • number (required) — number — The starting number
  • percent (required) — number — The percentage to add on

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_position_size_calculator read-only

  Work out how large a position to take so that hitting the stop-loss loses only a chosen percentage of the account. Enter account size, risk percentage, entry price and stop-loss price. Returns units to buy, position value, amount at risk and stop distance. Figures are treated as GBP. Source: https://hopi.co.uk/position-size-calculator/

  Parameters:

  • account (required) — number — Total account size
  • risk (required) — number — Percentage of the account to risk on this trade (above 0, up to 100)
  • entry (required) — number — Entry price per unit
  • stop (required) — number — Stop-loss price per unit

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_power_converter read-only

  Convert power from one unit to another. Units: w (watts), kw (kilowatts), hp (mechanical horsepower), ps (metric horsepower, PS). Source: https://hopi.co.uk/power-converter/

  Parameters:

  • value (required) — number — The power value to convert
  • from (required) — string — Unit to convert from
  • to (required) — string — Unit to convert to

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_pressure_converter read-only

  Convert pressure from one unit to another. Units: bar, psi (pounds per square inch), kpa (kilopascals), atm (atmospheres). Source: https://hopi.co.uk/pressure-converter/

  Parameters:

  • value (required) — number — The pressure value to convert
  • from (required) — string — Unit to convert from
  • to (required) — string — Unit to convert to

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_prime_factorisation_calculator read-only

  Check whether a whole number (2 to 1,000,000,000,000,000) is prime, break it into its prime factors in power form, count its divisors, and list them. Uses trial division. Source: https://hopi.co.uk/prime-factorisation-calculator/

  Parameters:

  • number (required) — integer — A whole number from 2 to 1,000,000,000,000,000

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_pro_rata_salary_calculator read-only

  Work out a pro rata salary for part-time hours by scaling a full-time salary by the ratio of your hours to full-time hours. Returns the pro rata yearly, monthly and weekly pay and the fraction of full-time. Amounts in GBP, gross before tax. Source: https://hopi.co.uk/pro-rata-salary-calculator/

  Parameters:

  • fullTimeSalary (required) — number — Full-time annual salary in GBP (greater than zero)
  • fullTimeHours (required) — number — Full-time hours per week (greater than zero)
  • hours (required) — number — Your hours per week (greater than zero)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_product_feed_generator read-only

  Turn product rows into a platform-valid product feed: Meta (Facebook and Instagram) RSS 2.0, Google Merchant RSS 2.0, Atom 1.0 or generic RSS 2.0, using the g: namespace where the platform expects it. Each row is validated (required fields, price as 12.99 GBP, availability and condition values, http links, unique ids); rows that fail are skipped and listed. Returns the XML, counts and errors. Source: https://hopi.co.uk/product-feed-generator/

  Parameters:

  • rows (required) — array — Product rows keyed by feed field name. Required per row: id, title, description, availability, condition, price, link, image_link, brand. Optional: sale_price, gtin, mpn, item_group_id, google_product_category, product_type, color, size, gender, age_group, shipping_weight, additional_image_link, quantity_to_sell_on_facebook.
  • link — string — Shop URL for the feed header (optional, must start with http:// or https://).
  • title — string — Feed title. Default Product feed.
  • currency — string — ISO 4217 currency code for prices, for example GBP. Default GBP.
  • platform — string — Feed format. Default meta.
  • description — string — Feed description (optional).

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_random_colour_generator read-only

  Generate a random colour and return its hex, RGB and HSL values. Each of the red, green and blue channels gets an independent value from 0 to 255. Source: https://hopi.co.uk/random-colour-generator/

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_random_coordinates read-only

  Generate random geographic coordinates that are uniform by surface area across the globe (points are not bunched at the poles). Returns latitude and longitude in decimal degrees. Source: https://hopi.co.uk/random-coordinates/

  Parameters:

  • decimals — integer — Decimal places for each coordinate, 2 to 6 (default 4)
  • quantity — integer — How many points to generate, 1 to 100 (default 1)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_random_letter_generator read-only

  Generate random letters from the alphabet, optionally limited to vowels or consonants. Returns the letters as a list. Source: https://hopi.co.uk/random-letter-generator/

  Parameters:

  • set — string — Which letters to draw from (default any)
  • quantity — integer — How many letters to generate, 1 to 100 (default 1)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_random_number_generator read-only

  Generate one or more random whole numbers within a range (inclusive), optionally with no repeats. Returns the numbers as a list. Source: https://hopi.co.uk/random-number-generator/

  Parameters:

  • min (required) — integer — Lowest possible number (inclusive)
  • max (required) — integer — Highest possible number (inclusive)
  • unique — boolean — If true, no number repeats (default false)
  • quantity — integer — How many numbers to generate, 1 to 1000 (default 1)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_random_team_generator read-only

  Shuffle a list of names and deal them evenly into a set number of teams. Returns each team's members. Source: https://hopi.co.uk/random-team-generator/

  Parameters:

  • names (required) — array — The list of names to split into teams
  • teams (required) — integer — How many teams to make, 2 to 20

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_random_word_generator read-only

  Generate random everyday English nouns, with no repeats. Returns the words as a list. Source: https://hopi.co.uk/random-word-generator/

  Parameters:

  • quantity — integer — How many words to generate, 1 to 20 (default 1)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_ratio_calculator read-only

  Work with ratios. Mode 'simplify': reduce a ratio a : b to its lowest terms, and give the 1 : n form and the decimal a / b. Mode 'solve': find the missing value x in the equivalent ratio a : b = c : x using cross multiplication. All inputs must be positive. Source: https://hopi.co.uk/ratio-calculator/

  Parameters:

  • mode (required) — string — 'simplify' a ratio, or 'solve' for the missing value
  • a (required) — number — First term of the ratio (positive)
  • b (required) — number — Second term of the ratio (positive)
  • c — number — Known term of the equivalent ratio, mode 'solve' (a : b = c : x)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_reading_time_calculator read-only

  Estimate how long a block of text takes to read. Returns a silent reading time (225 words per minute) and a read-aloud time (130 words per minute), along with the word count. Source: https://hopi.co.uk/reading-time-calculator/

  Parameters:

  • text (required) — string — The text to measure

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_redundancy_pay_calculator read-only

  Work out UK statutory redundancy pay for redundancies on or after 6 April 2026, using the gov.uk count-back method: for each full year of service (up to 20), 1.5 weeks if worked aged 41+, 1 week aged 22 to 40, and 0.5 weeks under 22. Weekly pay is capped at £751 and the total at £22,530. At least 2 full years of service are needed. Amounts in GBP. Source: https://hopi.co.uk/redundancy-pay-calculator/

  Parameters:

  • age (required) — integer — Age at redundancy (15 to 100)
  • years (required) — integer — Full years of continuous service (0 to 60, cannot exceed age)
  • weeklyPay (required) — number — Gross weekly pay in GBP

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_remove_duplicate_lines read-only

  Remove duplicate lines from a block of text, keeping the first occurrence of each line in its original order. Can optionally ignore letter case when deciding what counts as a duplicate. Returns the deduplicated text plus how many lines were kept and removed. Source: https://hopi.co.uk/remove-duplicate-lines/

  Parameters:

  • text (required) — string — The text to deduplicate, one item per line
  • caseInsensitive — boolean — Treat lines that differ only in case as duplicates (default false)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_remove_extra_spaces read-only

  Tidy up spacing in text: collapse runs of spaces, tabs and non-breaking spaces down to a single space and trim each line. Can optionally also remove blank lines. Line breaks between lines are kept. Source: https://hopi.co.uk/remove-extra-spaces/

  Parameters:

  • text (required) — string — The text to clean
  • removeBlankLines — boolean — Also drop empty lines (default false)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_remove_line_breaks read-only

  Remove line breaks from text. In 'spaces' mode every line is joined into one with single spaces. In 'paragraphs' mode blank lines are treated as paragraph breaks, so text is joined within each paragraph while the blank line between paragraphs is preserved. Source: https://hopi.co.uk/remove-line-breaks/

  Parameters:

  • text (required) — string — The text to join
  • mode — string — 'spaces' joins everything into one block (default), 'paragraphs' keeps paragraph breaks

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_reverse_text read-only

  Reverse text in one of three ways. 'characters' reverses the entire text character by character. 'words' reverses the order of words on each line. 'each' keeps the word order but reverses the letters within each word. Source: https://hopi.co.uk/reverse-text/

  Parameters:

  • text (required) — string — The text to reverse
  • mode — string — 'characters' (default), 'words' reverses word order per line, 'each' reverses letters within each word

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_rgb_to_hex read-only

  Convert red, green and blue values (each a whole number from 0 to 255) to an uppercase hex colour code. Source: https://hopi.co.uk/rgb-to-hex/

  Parameters:

  • r (required) — integer — Red, 0 to 255
  • g (required) — integer — Green, 0 to 255
  • b (required) — integer — Blue, 0 to 255

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_ring_size_converter read-only

  Convert a ring size between UK, US and millimetre scales. Mode 'uk' takes a UK letter F to Z (add 1/2 for half sizes, e.g. 'N' or 'N 1/2'). Mode 'us' takes a US number 2.75 to 12.75. Mode 'mm' takes an inside circumference in mm (about 44 to 69). Returns UK size, US size, circumference and inside diameter. Source: https://hopi.co.uk/ring-size-converter/

  Parameters:

  • value (required) — string — The ring size to convert: a UK letter (uk mode), or a number (us or mm mode)
  • mode (required) — string — Which scale the value is in

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_robots_txt_generator read-only

  Build a robots.txt file from allow and disallow rules grouped by user agent, with an optional sitemap line. You can pass a preset ('allow' all, 'block' all, 'wordpress') or your own rules array. Source: https://hopi.co.uk/robots-txt-generator/

  Parameters:

  • rules — array — Custom rules, each an object with agent, directive and path
  • preset — string — Use a ready-made rule set instead of custom rules
  • sitemap — string — Optional sitemap URL for the Sitemap line

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_roman_numerals_converter read-only

  Convert between numbers and Roman numerals, both directions, for whole numbers from 1 to 3999. Give a number (e.g. 2026) to get its numeral, or a Roman numeral (e.g. MMXXVI) to get the number. The direction is detected automatically from the input. Source: https://hopi.co.uk/roman-numerals-converter/

  Parameters:

  • value (required) — string — A whole number from 1 to 3999, or a Roman numeral using I, V, X, L, C, D and M

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_rounding_calculator read-only

  Round a number to a chosen number of decimal places or significant figures, with halves always rounded up (away from zero). Mode 'dp': decimal places, 0 to 12. Mode 'sf': significant figures, 1 to 15. Source: https://hopi.co.uk/rounding-calculator/

  Parameters:

  • number (required) — number — The number to round
  • mode (required) — string — 'dp' for decimal places, or 'sf' for significant figures
  • count (required) — integer — How many decimal places (0 to 12) or significant figures (1 to 15)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_running_pace_calculator read-only

  Work out running pace, finish time or distance, in kilometres or miles. Mode 'pace' needs distance and timeSeconds; mode 'time' needs distance and paceSeconds (seconds per unit); mode 'distance' needs timeSeconds and paceSeconds. Distance is in the chosen unit. Returns pace per km and per mile, speed in km/h and mph, distance and total time. Source: https://hopi.co.uk/running-pace-calculator/

  Parameters:

  • mode (required) — string — Which value to solve for
  • unit — string — Unit for distance and the given pace. Default 'km'
  • distance — number — Distance in the chosen unit (needed for 'pace' and 'time' modes)
  • paceSeconds — number — Pace in seconds per unit (needed for 'time' and 'distance' modes)
  • timeSeconds — number — Total time in seconds (needed for 'pace' and 'distance' modes)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_satoshi_converter read-only

  Convert satoshis to BTC, mBTC and bits, or convert BTC to satoshis, mBTC and bits. Uses exact whole-satoshi integer maths. 1 BTC is 100,000,000 satoshis. Source: https://hopi.co.uk/satoshi-converter/

  Parameters:

  • mode (required) — string — Direction of conversion
  • value (required) — string — The amount to convert: whole satoshis for sats_to_btc, or a BTC amount for btc_to_sats

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_savings_goal_calculator read-only

  Plan a savings goal, compounded monthly. Mode 'time' works out how long a monthly deposit takes to reach a target. Mode 'monthly' works out the monthly saving needed to reach a target within a number of years. Both take an optional starting balance and an annual interest rate. Amounts in GBP. Source: https://hopi.co.uk/savings-goal-calculator/

  Parameters:

  • mode (required) — string — 'time' finds the time to reach the goal; 'monthly' finds the monthly saving needed
  • target (required) — number — Savings target in GBP (greater than zero)
  • rate (required) — number — Annual interest rate as a percentage
  • start — number — Starting balance in GBP (default 0)
  • years — number — Monthly mode: number of years to reach the goal
  • monthly — number — Time mode: monthly deposit in GBP

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_schema_markup_generator read-only

  Build valid JSON-LD structured data using schema.org. Supports FAQ pages, articles, local businesses and breadcrumb lists. Returns the JSON-LD object and a ready-to-paste script snippet. Source: https://hopi.co.uk/schema-markup-generator/

  Parameters:

  • type (required) — string — The schema type to build
  • url — string — For type 'local': website URL
  • faqs — array — For type 'faq': questions and answers
  • name — string — For type 'local': business name
  • town — string — For type 'local': town or locality
  • hours — string — For type 'local': opening hours
  • items — array — For type 'breadcrumb': ordered pages
  • phone — string — For type 'local': telephone
  • author — string — For type 'article': author name
  • street — string — For type 'local': street address
  • headline — string — For type 'article': the headline
  • modified — string — For type 'article': date modified
  • postcode — string — For type 'local': postal code
  • published — string — For type 'article': date published

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_scientific_calculator read-only

  Evaluate a maths expression following the standard order of operations (BODMAS). Supports + - * / ^ (power), ! (factorial), % (as divide by 100), brackets, the constants pi and e, and the functions sin, cos, tan, asin, acos, atan, ln, log (base 10) and sqrt. Set angleMode to 'deg' (default) or 'rad' for trigonometry. Source: https://hopi.co.uk/scientific-calculator/

  Parameters:

  • expression (required) — string — The maths expression, e.g. '2 + 3 * 4', 'sin(30)', 'sqrt(2)^2', '5!'
  • angleMode — string — Angle units for trigonometry: 'deg' (default) or 'rad'

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_secret_santa_generator read-only

  Draw Secret Santa gift pairings from a list of names. Every person gives to exactly one other person, and nobody is assigned to themselves (a derangement). Returns the giver to receiver pairs. Source: https://hopi.co.uk/secret-santa-generator/

  Parameters:

  • names (required) — array — The list of participant names (at least two, no duplicates)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_set_for_life_generator read-only

  Generate random UK Set For Life lines. Each line has 5 main numbers from 1 to 47 (unique, sorted low to high) plus one Life Ball from 1 to 10, drawn with cryptographic randomness. Draws are Monday and Thursday; the top prize is £10,000 a month for 30 years at odds of 1 in 15,339,390. Source: https://hopi.co.uk/set-for-life-generator/

  Parameters:

  • lines — integer — How many lines to generate, 1 to 10 (default 1)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_shoe_size_converter read-only

  Convert a UK shoe size to approximate EU and US sizes. Set sex to 'men' (UK 5 to 13) or 'women' (UK 2 to 9). UK size must be in whole or half steps. Source: https://hopi.co.uk/shoe-size-converter/

  Parameters:

  • ukSize (required) — number — UK shoe size (whole or half, e.g. 8 or 8.5)
  • sex (required) — string — Which sizing chart to use

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_sleep_calculator read-only

  Suggest sleep times using 90-minute cycles plus 15 minutes to fall asleep. Mode 'wake' takes a wake time and returns the best bedtimes (wake - 15 - cycles x 90 minutes). Mode 'bedtime' takes a bedtime and returns the best wake times (bedtime + 15 + cycles x 90 minutes). Both return options for 6, 5, 4 and 3 cycles. Times are 'HH:MM' 24-hour. Source: https://hopi.co.uk/sleep-calculator/

  Parameters:

  • mode (required) — string — 'wake' to find bedtimes from a wake time, or 'bedtime' to find wake times from a bedtime
  • time (required) — string — The known time as 'HH:MM' (24-hour): the wake time for mode 'wake', or the bedtime for mode 'bedtime'

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_slot_machine_picker read-only

  Spin a slot machine reel of names or options and pick one at random. Every item has an equal chance. Returns the chosen item. Source: https://hopi.co.uk/slot-machine-picker/

  Parameters:

  • items (required) — array — The list of names or options on the reel (at least two)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_slug_generator read-only

  Turn any title or text into a clean URL slug: lowercase, accents stripped, and every run of spaces, punctuation and symbols collapsed to a single hyphen, with hyphens trimmed from the ends. Source: https://hopi.co.uk/slug-generator/

  Parameters:

  • text (required) — string — The title or text to slugify

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_small_text_generator read-only

  Convert text into decorative Unicode styles. 'superscript' uses tiny raised characters, 'smallcaps' uses small capital letters, and 'fullwidth' uses wide monospaced characters. Any character with no styled equivalent is left unchanged. Source: https://hopi.co.uk/small-text-generator/

  Parameters:

  • text (required) — string — The text to convert
  • style — string — Which style to apply (default superscript)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_special_characters read-only

  List special characters and symbols grouped by category: arrows, stars and hearts, maths, currency, punctuation, legal marks and accents. Optionally filter to a single group. Returns the characters ready to copy. Source: https://hopi.co.uk/special-characters/

  Parameters:

  • group — string — Optional: return only this group. Omit to return every group.

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_speed_converter read-only

  Convert a speed from one unit to another. Units: mph (miles per hour), kmh (kilometres per hour), ms (metres per second), kn (knots), mach (Mach, at 340.29 m/s). Source: https://hopi.co.uk/speed-converter/

  Parameters:

  • value (required) — number — The speed value to convert
  • from (required) — string — Unit to convert from
  • to (required) — string — Unit to convert to

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_spin_the_bottle read-only

  Spin the bottle and pick one player at random from those in the circle. Every player has an equal chance. Returns the chosen player. Source: https://hopi.co.uk/spin-the-bottle/

  Parameters:

  • players (required) — array — The list of players in the circle (at least two)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_sql_formatter read-only

  Format a SQL query: uppercase the keywords, put each clause on its own line and indent conditions, while leaving quoted strings, identifiers, numbers and comments untouched. Only whitespace and keyword case change. Source: https://hopi.co.uk/sql-formatter/

  Parameters:

  • sql (required) — string — The SQL query to format

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_staking_calculator read-only

  Turn a quoted staking rate into a final balance and rewards earned. For an APR rate, choose daily or monthly compounding; for an APY rate, compounding is already included. Returns the final balance, rewards earned and the effective APY. Figures are treated as GBP. Source: https://hopi.co.uk/staking-calculator/

  Parameters:

  • principal (required) — number — Amount staked
  • rate (required) — number — Quoted rate as a percentage (0 to 1000)
  • years (required) — number — Term in years (above 0, up to 100)
  • rateType — string — Whether the rate is APR (needs compounding) or APY (default apr)
  • compounding — string — Compounding frequency for APR (default daily)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_stamp_duty_calculator read-only

  Work out Stamp Duty Land Tax (SDLT) on a property purchase in England and Northern Ireland. Buyer types: 'ftb' first-time buyer (relief up to £500,000, standard rates above), 'home' moving home (main residence), 'additional' second home or buy-to-let (higher rates, only from £40,000). Returns the tax due and the effective rate. Amounts in GBP. Scotland (LBTT) and Wales (LTT) have their own rates. Source: https://hopi.co.uk/stamp-duty-calculator/

  Parameters:

  • price (required) — number — Property purchase price in GBP
  • buyer (required) — string — 'ftb' first-time buyer, 'home' moving home, 'additional' second home or buy-to-let

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_standard_deviation_calculator read-only

  Work out the sample and population standard deviation, sample and population variance, mean and count from a list of numbers. Provide the numbers separated by spaces, commas, semicolons or new lines. Sample figures need at least two values. Source: https://hopi.co.uk/standard-deviation-calculator/

  Parameters:

  • numbers (required) — string — A list of numbers separated by spaces, commas, semicolons or new lines

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_star_sign_calculator read-only

  Find the western zodiac star sign for a date of birth. Dates use the YYYY-MM-DD format (only the month and day matter). Returns the sign, its symbol, date range and element. Source: https://hopi.co.uk/star-sign-calculator/

  Parameters:

  • date (required) — string — Date of birth in YYYY-MM-DD format

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_stone_to_kg read-only

  Convert a UK body weight given in stones and pounds to kilograms and grams. Uses exactly 14 pounds to the stone and 0.45359237 kg to the pound. Pounds are optional; give 11 st 7 lb as stone 11, pounds 7. Source: https://hopi.co.uk/stone-to-kg/

  Parameters:

  • stone (required) — number — Whole or decimal stones
  • pounds — number — Extra pounds on top of the stones (0 to 13.99, optional)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_student_loan_calculator read-only

  Work out UK student loan repayments from an annual salary using 2026/27 thresholds. Plans: 'p1' Plan 1 (9% above £26,900), 'p2' Plan 2 (9% above £29,385), 'p4' Plan 4 (9% above £33,795), 'p5' Plan 5 (9% above £25,000), 'pg' Postgraduate Loan (6% above £21,000). An undergraduate plan can optionally add a Postgraduate Loan on top. Returns yearly and monthly repayments. Amounts in GBP. Source: https://hopi.co.uk/student-loan-calculator/

  Parameters:

  • salary (required) — number — Annual salary in GBP
  • plan (required) — string — Repayment plan
  • addPostgraduate — boolean — Add a Postgraduate Loan on top of an undergraduate plan (ignored when plan is pg; default false)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_take_home_pay_calculator read-only

  Work out UK take-home pay from an annual gross salary for the 2026/27 tax year in England, Wales and Northern Ireland, using code 1257L income tax bands (20/40/45%) with personal allowance taper above £100,000, plus employee National Insurance. Returns net pay per year, month and week, and the tax and NI deducted. Amounts in GBP. Source: https://hopi.co.uk/take-home-pay-calculator/

  Parameters:

  • salary (required) — number — Annual gross salary in GBP

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_tarot_reader read-only

  Draw a tarot spread from all 78 Rider-Waite-Smith cards, dealt without replacement using cryptographic randomness. Spreads: daily (1 card), past-present-future (3), situation (3: situation, obstacle, advice), decision (5), relationship (6), career (5), celtic (10, Celtic Cross). Returns each position with its card, orientation and keywords, plus counts of Major Arcana and reversed cards. For reflection and fun, not prediction. Source: https://hopi.co.uk/tarot-reader/

  Parameters:

  • spread (required) — string — Which spread to draw
  • reversed — boolean — Allow reversed cards (default true)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_tdee_calculator read-only

  Estimate daily calories (TDEE) and BMR using the Mifflin-St Jeor equation. BMR = 10 x kg + 6.25 x cm - 5 x age + (5 for male, -161 for female). TDEE = BMR x activity factor (sedentary 1.2, light 1.375, moderate 1.55, active 1.725, very_active 1.9). Use units 'metric' (heightCm, weightKg) or 'imperial' (heightInches, weightPounds). Also returns mild-loss (-250), loss (-500) and gain (+500) calorie goals. Source: https://hopi.co.uk/tdee-calculator/

  Parameters:

  • sex (required) — string — Biological sex
  • age (required) — number — Age in years
  • units (required) — string — 'metric' (cm, kg) or 'imperial' (inches, pounds)
  • activity — string — Activity level, default 'moderate'
  • heightCm — number — Height in centimetres (metric)
  • weightKg — number — Weight in kilograms (metric)
  • heightInches — number — Total height in inches (imperial)
  • weightPounds — number — Weight in pounds (imperial)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_test_card_number_generator read-only

  Generate Luhn-valid TEST card numbers for QA and development, or validate a card number. Test numbers pass the Luhn checksum and match a real brand format but are NOT real accounts, are linked to no one, and cannot be charged. Generate mode returns numbers for a brand (Visa, Mastercard, American Express, Discover); validate mode returns whether a number passes Luhn and its detected brand. Runs on Hopi's server; nothing is stored and no bank is contacted. Source: https://hopi.co.uk/test-card-number-generator/

  Parameters:

  • mode — string — Generate test numbers, or validate a supplied number (default generate)
  • brand — string — Card brand to generate (default visa)
  • count — integer — How many numbers to generate, 1 to 50 (default 10)
  • number — string — For validate mode: the card number to check (spaces and dashes are ignored)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_text_repeater read-only

  Repeat a piece of text a chosen number of times, joined by an optional separator, with optional line numbering. Count is capped at 10000 repeats and the output is capped at 100000 characters. Returns the repeated text plus its character and line counts. Source: https://hopi.co.uk/text-repeater/

  Parameters:

  • text (required) — string — The text to repeat
  • count (required) — integer — How many times to repeat it (1 to 10000)
  • numbering — boolean — Prefix each repeat with a number, e.g. '1. ' (default false)
  • separator — string — How to join the repeats (default none)
  • customSeparator — string — The separator string to use when separator is 'custom'

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_text_splitter read-only

  Split a long block of text into smaller blocks. In 'length' mode it splits into chunks up to a maximum character size, breaking at spaces where possible, and can add 1/n numbering to each block. In 'delimiter' mode it splits wherever a delimiter appears (use \n for newline, \t for tab). Returns the list of blocks. Source: https://hopi.co.uk/text-splitter/

  Parameters:

  • text (required) — string — The text to split
  • mode — string — 'length' splits by character size (default), 'delimiter' splits at a delimiter
  • size — integer — Maximum characters per block for length mode (at least 10, default 280)
  • numbered — boolean — Add ' n/total' numbering to each block in length mode (default false)
  • delimiter — string — The delimiter for delimiter mode; \n and \t are interpreted as newline and tab

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_thunderball_generator read-only

  Generate random UK Thunderball lines. Each line has 5 main numbers from 1 to 39 (unique, sorted low to high) plus one Thunderball from 1 to 14, drawn with cryptographic randomness. Draws are Tuesday, Wednesday, Friday and Saturday; the fixed top prize is £500,000 at odds of 1 in 8,060,598. Source: https://hopi.co.uk/thunderball-generator/

  Parameters:

  • lines — integer — How many lines to generate, 1 to 10 (default 1)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_time_calculator read-only

  Add or subtract two durations, each given as hours and minutes. Returns the total as an H:MM clock value, as decimal hours, and as total minutes. Results can be negative when subtracting. Source: https://hopi.co.uk/time-calculator/

  Parameters:

  • hours1 — number — Hours of the first duration (default 0)
  • hours2 — number — Hours of the second duration (default 0)
  • minutes1 — number — Minutes of the first duration (default 0)
  • minutes2 — number — Minutes of the second duration (default 0)
  • operation — string — Add or subtract the second duration from the first (default 'add')

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_time_zone_converter read-only

  Convert a wall-clock date and time from one time zone to another, using the server's IANA time zone data (so daylight saving is handled). Date uses YYYY-MM-DD and time uses 24-hour HH:MM. Zones are IANA identifiers such as Europe/London or America/New_York. Returns the converted time, the day difference, and both UTC offsets. Source: https://hopi.co.uk/time-zone-converter/

  Parameters:

  • date (required) — string — The date in the source zone, YYYY-MM-DD format
  • time (required) — string — The time in the source zone, 24-hour HH:MM format
  • fromZone (required) — string — Source IANA time zone, e.g. Europe/London
  • toZone (required) — string — Target IANA time zone, e.g. America/New_York

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_tip_calculator read-only

  Work out a tip on a bill and optionally split the total between people. Returns the tip amount, the total, and the amount per person. Source: https://hopi.co.uk/tip-calculator/

  Parameters:

  • bill (required) — number — The bill amount before tip
  • split — integer — Number of people to split between (default 1)
  • tipPercent — number — Tip as a percentage (default 12.5)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_triangle_calculator read-only

  Solve a right-angle triangle from any two given values, at least one of which must be a side. Sides: a (opposite), b (adjacent), c (hypotenuse). angleA is angle A in degrees, between 0 and 90 (the third angle is the 90 degree right angle). Returns all three sides, both non-right angles, the area and the perimeter. Source: https://hopi.co.uk/triangle-calculator/

  Parameters:

  • a — number — Side a, the opposite (greater than 0)
  • b — number — Side b, the adjacent (greater than 0)
  • c — number — Side c, the hypotenuse (greater than 0, must be the longest side)
  • angleA — number — Angle A in degrees, strictly between 0 and 90

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_ucas_points_calculator read-only

  Add up UCAS tariff points from A-level grades using the current tariff: A* 56, A 48, B 40, C 32, D 24, E 16. Give the number of grades at each level. Returns the total points and the number of grades counted. Source: https://hopi.co.uk/ucas-points-calculator/

  Parameters:

  • a — integer — Number of A grades (0 to 20)
  • b — integer — Number of B grades (0 to 20)
  • c — integer — Number of C grades (0 to 20)
  • d — integer — Number of D grades (0 to 20)
  • e — integer — Number of E grades (0 to 20)
  • aStar — integer — Number of A* grades (0 to 20)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_unicode_inspector read-only

  Inspect text as Unicode. Returns the number of code points (iterated so emoji and other astral characters count as one), the UTF-16 length, the UTF-8 byte count, and per-character details: the character, its code point as U+XXXX, its decimal value, its UTF-8 bytes as hex, its HTML entity and a JavaScript escape. The character list is capped at 2000 entries. Source: https://hopi.co.uk/unicode-inspector/

  Parameters:

  • text (required) — string — The text to inspect

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_unit_price_calculator read-only

  Compare the unit price of two or more items to find the best value. Each item has a price in GBP, a quantity and a unit ('g', 'kg', 'ml', 'l' or 'each'). Weights are compared per kg, volumes per litre, and counts each. Returns the unit price of every item and which is cheapest. Source: https://hopi.co.uk/unit-price-calculator/

  Parameters:

  • items (required) — array — The items to compare (at least two)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_unix_timestamp_converter read-only

  Convert between Unix epoch timestamps and readable dates. Pass a timestamp to get the UTC and local date (seconds or milliseconds detected automatically), or pass a date (and optional time, interpreted in local time) to get the timestamp in seconds and milliseconds. Source: https://hopi.co.uk/unix-timestamp-converter/

  Parameters:

  • date — string — A date as YYYY-MM-DD. Provide this to convert a date to a timestamp.
  • time — string — Optional time as HH:MM:SS to accompany 'date' (default 00:00:00), in local time.
  • timestamp — string — A Unix timestamp in seconds or milliseconds (may be negative). Provide this to convert a timestamp to a date.

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_upside_down_text read-only

  Flip text upside down using Unicode look-alike characters and reverse its order, so it reads as if rotated 180 degrees. Characters with no upside-down equivalent are kept as they are (but still reversed in position). Source: https://hopi.co.uk/upside-down-text/

  Parameters:

  • text (required) — string — The text to flip upside down

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_url_encoder read-only

  Percent-encode or decode text for URLs. Component mode encodes every reserved character (right for a single query value); whole-URL mode leaves structural characters like / ? & alone (right for a complete address). Source: https://hopi.co.uk/url-encoder/

  Parameters:

  • text (required) — string — The text or URL to encode or decode
  • mode — string — 'component' for a single value, 'uri' for a whole URL (default 'component')
  • action — string — Whether to encode or decode (default 'encode')

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_url_parser read-only

  Parse a URL into its parts: protocol, host, port, path, fragment, origin and every decoded query parameter. If no scheme is given, https:// is assumed for a bare domain. Source: https://hopi.co.uk/url-parser/

  Parameters:

  • url (required) — string — The URL to parse

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_user_agent_parser read-only

  Parse a user agent string into its parts: browser and version, rendering engine, operating system and version, device type (mobile, tablet or desktop) and whether it looks like a bot or crawler. Uses an ordered pattern table (Edge before Chrome, Chrome before Safari). User agent strings can be spoofed, so results are best-effort, not proof. Source: https://hopi.co.uk/user-agent-parser/

  Parameters:

  • ua (required) — string — The user agent string to parse

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_username_generator read-only

  Invent memorable usernames by pairing a random adjective with a random noun, optionally with a two-digit number on the end. Returns a list of unique usernames. Source: https://hopi.co.uk/username-generator/

  Parameters:

  • count — integer — How many usernames to generate, 1 to 50 (default 6)
  • addNumbers — boolean — Append a two-digit number to each name (default false)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_utm_link_generator read-only

  Add UTM campaign parameters (utm_source, utm_medium, utm_campaign, utm_term, utm_content) to a URL without breaking existing query parameters. Warns on mixed case and notes any missing core parameters. Only http and https URLs are accepted. Source: https://hopi.co.uk/utm-link-generator/

  Parameters:

  • url (required) — string — The base URL to tag (https:// assumed if no scheme given)
  • utm_term — string — Paid keyword term (optional)
  • utm_medium — string — The marketing medium, e.g. email
  • utm_source — string — Where the traffic comes from, e.g. newsletter
  • utm_content — string — Content variant, e.g. button vs text link (optional)
  • utm_campaign — string — The campaign name

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_uuid_generator read-only

  Generate 1 to 100 random version 4 UUIDs using a cryptographically secure random source. Never uses Math.random. Source: https://hopi.co.uk/uuid-generator/

  Parameters:

  • count — integer — How many UUIDs to generate, 1 to 100 (default 1)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_vat_calculator read-only

  Add UK VAT to a net amount, or remove VAT from a gross (VAT-inclusive) amount. Default rate is the UK standard 20 percent. Returns the net, VAT and gross figures. Source: https://hopi.co.uk/vat-calculator/

  Parameters:

  • amount (required) — number — The money amount
  • mode (required) — string — 'add' VAT to a net amount, or 'remove' VAT from a gross amount
  • rate — number — VAT rate as a percentage (default 20)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_vigenere_cipher read-only

  Encode or decode text with the classic Vigenere cipher using a keyword. Each letter is shifted by the matching keyword letter (A is 0 to Z is 25), the keyword repeating across the message. Only A to Z letters are changed and case is preserved; numbers, spaces and punctuation pass through unchanged and do not advance the keyword. The keyword uses only its letters. Decoding reverses the shift. Source: https://hopi.co.uk/vigenere-cipher/

  Parameters:

  • key (required) — string — The keyword (only its A to Z letters are used)
  • text (required) — string — The text to transform
  • mode — string — 'encode' to apply the cipher, 'decode' to reverse it (default encode)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_volume_converter read-only

  Convert a volume from one unit to another. Units: ml (millilitres), l (litres), ukpt (UK pints), ukgal (UK gallons), usgal (US gallons), ukfloz (UK fluid ounces), usfloz (US fluid ounces), m3 (cubic metres). Source: https://hopi.co.uk/volume-converter/

  Parameters:

  • value (required) — number — The volume value to convert
  • from (required) — string — Unit to convert from
  • to (required) — string — Unit to convert to

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_water_intake_calculator read-only

  Estimate a rough daily fluid target from body weight, using 30 to 35 ml per kg, plus an activity add (sedentary 0, light 250, moderate 500, active 750, very_active 1000 ml) and 500 ml more for hot conditions. Use units 'metric' (weightKg) or 'imperial' (weightStone and weightPounds). Returns a low-to-high range in litres, millilitres and 250 ml glasses. Source: https://hopi.co.uk/water-intake-calculator/

  Parameters:

  • units (required) — string — 'metric' (kg) or 'imperial' (stone and pounds)
  • hot — boolean — Add 500 ml for hot conditions. Default false
  • activity — string — Activity level, default 'sedentary'
  • weightKg — number — Weight in kilograms (metric)
  • weightStone — number — Whole stone part of weight (imperial)
  • weightPounds — number — Pounds part of weight (imperial)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_week_number read-only

  Find the ISO 8601 week number for a date. Dates use the YYYY-MM-DD format and default to today. ISO weeks run Monday to Sunday and week 1 holds the year's first Thursday. Returns the week number, ISO year, and the Monday and Sunday of that week. Source: https://hopi.co.uk/week-number/

  Parameters:

  • date — string — Optional date in YYYY-MM-DD format (defaults to today)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_weight_converter read-only

  Convert a weight from one unit to another. Units: g (grams), kg (kilograms), oz (ounces), lb (pounds), st (stone). Source: https://hopi.co.uk/weight-converter/

  Parameters:

  • value (required) — number — The weight value to convert
  • from (required) — string — Unit to convert from
  • to (required) — string — Unit to convert to

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_wheel_spinner read-only

  Spin a wheel of names or options and pick one at random. Every item has an equal chance. Returns the chosen item. Source: https://hopi.co.uk/wheel-spinner/

  Parameters:

  • items (required) — array — The list of names or options on the wheel (at least two)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_word_counter read-only

  Analyse a block of text and return the word count, character count (with and without spaces), sentence count, paragraph count and an estimated reading time at 225 words per minute. Source: https://hopi.co.uk/word-counter/

  Parameters:

  • text (required) — string — The text to analyse

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_word_frequency_counter read-only

  Count how often each word appears in a block of text, sorted from most to least frequent. Returns the total word count, the number of unique words, and the top 20 words with their counts and percentages. Common stop words (the, and, of, ...) can optionally be ignored. Source: https://hopi.co.uk/word-frequency-counter/

  Parameters:

  • text (required) — string — The text to analyse
  • ignoreStopwords — boolean — Ignore common words such as the, and, of, to (default false)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_working_days_calculator read-only

  Count the working days (Monday to Friday) between two dates, inclusive of both ends, optionally excluding England and Wales bank holidays. Dates use the YYYY-MM-DD format. Bank holiday data covers 2026 and 2027 only, so outside those years just weekends are excluded. Source: https://hopi.co.uk/working-days-calculator/

  Parameters:

  • from (required) — string — Start date in YYYY-MM-DD format
  • to (required) — string — End date in YYYY-MM-DD format
  • bankHolidays — boolean — Exclude England and Wales bank holidays as well as weekends (default true)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_would_you_rather_generator read-only

  Draw original, family-friendly would-you-rather pairs, open icebreaker questions or rapid-fire this-or-that pairs, optionally filtered by category. Would-you-rather categories: silly, food, travel, work, deep, kids. Icebreaker categories: work, party, deep, kids. This-or-that has no categories. Returns distinct items drawn at random. Source: https://hopi.co.uk/would-you-rather-generator/

  Parameters:

  • mode (required) — string — Which list to draw from
  • count — integer — How many to draw, 1 to 20 (default 1)
  • category — string — Optional category filter (would-you-rather: silly, food, travel, work, deep, kids; icebreaker: work, party, deep, kids). Omit for all.

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_yes_no_wheel read-only

  Get a random yes or no decision, with an optional maybe. Returns the answer. Source: https://hopi.co.uk/yes-no-wheel/

  Parameters:

  • allowMaybe — boolean — Include 'maybe' as a possible answer (default false)

  Hints: read-only yes · destructive no · idempotent yes · open-world no

• hopi_zero_width_text_hider read-only

  Hide a secret message inside ordinary text using invisible zero-width Unicode characters, reveal a message hidden that way, or clean zero-width characters out of text. Mode 'hide' takes cover and secret (optional spread to distribute the invisible run between words) and returns the output text plus the number of invisible characters added (UTF-8 bytes x 4 + 1 end marker). Mode 'reveal' takes text and returns the decoded message, or an error if nothing is hidden. Mode 'clean' takes text and strips U+200B, U+200C, U+200D, U+2060, U+FEFF, U+180E and U+00AD, reporting how many were removed. This is hiding, not encryption. Source: https://hopi.co.uk/zero-width-text-hider/

  Parameters:

  • mode (required) — string — hide, reveal or clean
  • text — string — Reveal and clean modes: the text to inspect
  • cover — string — Hide mode: the visible cover text that carries the message
  • secret — string — Hide mode: the message to hide
  • spread — boolean — Hide mode: distribute the invisible run evenly between words instead of placing it after the first word

  Hints: read-only yes · destructive no · idempotent yes · open-world no

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