MCP serveruk.co.hopi/hopi

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 da

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 live

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

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) o

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/

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 m

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

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 th

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 multipl

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:/

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

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, an

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 main

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

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 '

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 e

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 mult

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. Sou

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

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:/

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/

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

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, At

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. Sour

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: h

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/

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/co

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,

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/

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

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/co

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,

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. S

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

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

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 declar

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 by

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 heade

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 powd

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

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

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

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://

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

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 b

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/day

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 acquire

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/

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

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 pric

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-e

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).

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 dat

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

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

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, regi

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 an

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 leadi

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

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: http

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/

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 pe

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

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

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 g

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 f

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 onl

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 fami

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 'karvo

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/

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 t

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;

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 earli

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/

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:

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: h

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 ru

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 a

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, t

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 clea

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 writte

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 elem

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 pri

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

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/

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 y

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/

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 li

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 paymen

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.

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 Lif

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/

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.

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

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; no

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 c

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.c

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

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 c

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 per

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

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 interes

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

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,

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% bet

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,

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 pe

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 requeste

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

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

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

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 abou

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 starti

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. Sourc

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-calculato

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 th

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/

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 pr

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/

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/

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: h

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

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

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

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. S

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/

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/

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/

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

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

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. Sourc

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 ag

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 dupli

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 betwee

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

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 r

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/

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 12.7

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 ow

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

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': significa

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); m

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

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 tar

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 sn

Evaluate a maths expression following the standard order of operations (BODMAS). Supports + - * / ^ (power), ! (factorial), % (as divide by 100), brackets, the constants pi and e,

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 rec

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

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 'bedt

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/

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

Convert text into decorative Unicode styles. 'superscript' uses tiny raised characters, 'smallcaps' uses small capital letters, and 'fullwidth' uses wide monospaced characters. Any

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. Retur

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://ho

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/

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 w

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

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

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, semic

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

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

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 a

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: s

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 (sedent

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

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

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

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 subtr

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

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/

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, betwe

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 t

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

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 k

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 optio

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 a

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 / ? & alo

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: ht

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 b

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

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 mis

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/

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://h

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

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

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

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 t

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/

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/

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.

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

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 hol

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: sil

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

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