hospitality.bill-split
Split a restaurant bill evenly, by item or by share, exactly to the penny, with the service charge shared in proportion.
Organisations / anterra
Anterra
Money, tax and invoicing capabilities for UK and Irish business software.
Published functions 200
finance.proration
Split an amount into the part used and the part unused over a billing period, losing nothing.
money.amount
A currency-tagged monetary amount held in integer minor units.
agri.field-area
Field area in square metres, hectares and acres from a boundary polygon of latitude/longitude points.
agri.fertiliser-application
Fertiliser product rate (kg/ha and total) to meet N, P2O5 and K2O targets from its analysis, limiting nutrient first.
fleet.mileage-allowance
HMRC approved mileage allowance payments for an employee's own vehicle: tax-free amount, taxable excess or relief.
math.exp
e to the power x from + - * / only, so TypeScript, Python and Rust return the same double for the same input.
money.split-even
Split an amount into n near-equal parts that add back up to exactly the whole.
fleet.tachograph-rest Unreviewed
Check daily and weekly rest against GB/EU drivers' hours: 11h daily (9h reduced, 3+9 split), 45h weekly (24h reduced).
inventory.eoq
Economic order quantity (Harris/Wilson): the order size that minimises ordering plus holding cost, in whole units.
math.sin-cos
Sine and cosine of an angle in radians from + - * / only, so every language returns the same doubles.
telecoms.call-rating
Rate a call from a rate deck: longest-prefix destination match, billing increments, connection fee and minimum charge.
validation.uk-postcode
Validate a UK postcode and normalise it to canonical upper case with one space before the inward code.
agri.feed-ration
Ration costing and dry matter intake from each feed's fresh weight, DM % and price per tonne, in exact money.
agri.gross-margin
Enterprise gross margin (output less variable costs), in total and per hectare or per head, in exact money.
auth.access-token
Issue an API's HS256 access token, read one from an Authorization header, and refuse revoked or superseded ones.
auth.jwt
Sign, verify and decode HS256 JSON Web Tokens (RFC 7519): signature, algorithm and exp/nbf/iat checked with leeway.
charity.gasds
Gift Aid Small Donations Scheme top-up for a tax year: the £8,000 limit, the matching rule and community buildings.
charity.gift-aid
Gift Aid a UK charity can claim on a donation: basic rate tax grossed up, 25p per £1 at 20%.
charity.reclaim-batch
Gift Aid claim totals for a period from donation records: donor lines, aggregated small gifts, tax due.
charts.stack
Stack several series for stacked bars and areas: on zero, normalised to 100%, or diverging around zero.
construction.cis-deduction
Construction Industry Scheme deduction (0, 20 or 30%) on the labour part of a subcontractor payment.
education.student-loan-repayment
A graduate's student or postgraduate loan repayment for a tax year, as Self Assessment works it out.
encoding.base64
Bytes to base64 and base64url text and back (RFC 4648), with strict decoding, identically in every language.
energy.solar-generation
Estimated annual solar PV generation by the MCS method: kWp x Kk x shade factor, per array and in total.
finance.tax.add-vat Unreviewed
Add VAT to a net amount using the rate in force on the date of supply.
finance.tax.remove-vat Unreviewed
Extract the VAT already included in a gross amount, using the rate in force on the date of supply.
finance.tax.vat-return Unreviewed
UK nine-box VAT return totals for a period from categorised sales and purchases (VAT Notice 700/12).
health.dose-weight-based Unreviewed
Weight-based dose (per kg) capped at a maximum single dose and rounded to a measurable volume, in exact micro-units.
inventory.abc-classification
ABC classes by annual consumption value (Pareto), with configurable cut-offs such as 80/15/5 and deterministic ties.
math.pow
base to the power exponent from + - * / only, exact by squaring for whole exponents, identical in every language.
math.round-div
Integer division with an explicit rounding mode, for money arithmetic that must not drift.
money.convert
Convert an amount to another currency at a supplied exact rate, with an explicit rounding mode.
payroll.minimum-wage-check Unreviewed
Check pay for a pay reference period against the minimum or living wage for age and apprenticeship.
payroll.national-insurance Unreviewed
Employee and employer Class 1 National Insurance for one payment by category letter, exact percentage method.
payroll.student-loan Unreviewed
Student loan or postgraduate loan deduction from one period's pay, by plan, rounded down to whole pounds.
property.rental-yield Unreviewed
Gross and net rental yield of a let property, in basis points, from annual rent, costs and value.
react.form.button React ^19 · TypeScript only
A form button in primary, secondary or warning style that stays focusable while loading (GOV.UK button).
retail.coupon-validate
Check a coupon against a basket: dates, usage limits, eligible products and minimum spend, with reason codes.
retail.loyalty-points
Loyalty points for a purchase: redeem in blocks, earn on what is paid, with tier multipliers.
retail.promotion-apply
Apply BOGOF, 3-for-2, percent off, amount off and multibuy deals to a basket, best for the customer, allocated to lines.
validation.iban
Check an IBAN against the ISO 13616 mod-97-10 checksum and the registered length for its country.
agri.growing-degree-days
Growing degree days (thermal time) from daily min/max temperatures, a base and an optional upper cap.
agri.milk-price
Milk price per litre and payment from a contract's base price, butterfat/protein adjustments and bonuses.
agri.seed-rate
Seed rate in kg/ha from target plants per m², thousand-grain weight and expected establishment.
agri.spray-mix Unreviewed
Sprayer tank mix: tank fills, and product and water per full and part tank, for an area, water volume and dose.
agri.stocking-rate
Stocking rate: livestock units and LU per hectare from animal numbers, by a published LU coefficient table.
agri.yield-per-hectare
Crop yield per hectare and per acre from harvested quantity and field area in any area unit, exactly, as decimal text.
auth.bearer-token
The token from an HTTP Authorization header of the form "Bearer <token>" (RFC 6750), or null if it has none.
auth.login-throttle
Allow a login attempt or lock the account out, from its recent failed attempts, with the seconds until it may retry.
auth.normalise-email
Trim an email address and lower-case its domain for storage and lookup, or null if it is not a plausible address.
auth.password-hash
Hash a password for storage as pbkdf2_sha256$iterations$salt$hash, verify one in constant time, and spot weak hashes.
auth.password-policy
Check a new password against a named policy (NIST SP 800-63B-4 by default): length, common passwords, name and email.
auth.validate-login
Check a login form (email, password): the normalised email to look up, or a message for each field to fix.
auth.validate-password-change
Check a change-password form: current password given and correct, new one meeting the policy and different.
auth.validate-registration
Validate a sign-up form (email, password, name) in one call, with a message per field, in the browser and the API alike.
banking.bacs-processing-date
Bacs three-day cycle: input, processing and entry (arrival) dates for a submission, skipping weekends and bank holidays.
banking.cheque-amount-words
The words and figures to write on a cheque: "One hundred and twenty pounds and fifty pence only", "£120.50".
banking.faster-payments-limit
Whether a Faster Payment fits the scheme maximum, the bank's per-payment limit and what is left of its daily limit.
banking.fees-cap
Apply a monthly fee cap to a list of account charges: charge up to the cap, waive the rest.
banking.overdraft-interest
Overdraft interest for a statement period from daily balances, with an interest-free buffer.
banking.savings-aer
AER (annual equivalent rate) from a gross nominal rate and how often interest is paid, to two decimal places.
charity.donation-matching
Employer match on a donation: a ratio in basis points, limited by a per-donor cap and a programme budget.
charity.fundraising-ratio
Cost to raise £1 and charitable spend ratio for a charity, in exact basis points.
charity.gift-aid-eligibility
Whether a UK donation qualifies for Gift Aid: declaration, enough tax paid, and the donor benefit limits.
charity.higher-rate-relief
A Gift Aid donor's extra tax relief at higher, intermediate, additional and top rates, by extending the tax bands.
charity.payroll-giving
UK Payroll Giving for one pay period: the donation comes off pay before PAYE, and the tax it saves the employee.
charity.regular-giving-schedule
Collection dates for a regular gift: monthly, quarterly or annual on a day, clamped to short months, after a lead time.
charity.restricted-funds
Allocate charity spending to restricted funds first, then unrestricted funds, never overdrawing a restricted fund.
charts.axis
Axis geometry as data: tick positions, tick marks, label anchors and gridlines for number, time and category axes.
charts.bar-chart
Complete bar chart geometry as data, grouped or stacked: plot area, axes, gridlines, bar rectangles, colours, legend.
charts.color
Hex colours to RGB and back, and sRGB channels to linear light and back, identically in every language.
charts.contrast
WCAG 2.x contrast ratio between two colours, and which text colour reads best on a background.
charts.downsample
Reduce a long series to a few points that keep its visual shape, by Largest-Triangle-Three-Buckets (LTTB).
charts.extent
The minimum and maximum of a series as [min, max], skipping gaps (null), or null when there is no value.
charts.format
Axis and label text for charts: tick numbers, SI prefixes (1.2k, 3.4M), percentages, dates and money.
charts.histogram-bins
Bin values into histogram bins on round edges, by Sturges' rule, Freedman-Diaconis, or a fixed width.
charts.interpolate-color
The colour at a point along a sequential or diverging ramp, mixed in OKLab so steps look even; hex in, hex out.
charts.layout
Chart layout: the plot area inside margins, legend items wrapped into rows, and greedy label collision avoidance.
charts.line-chart
Complete line chart geometry as data: plot area, number or date axes, gridlines, series paths, colours, legend.
charts.palette
A categorical palette of n colour-blind-safe colours for chart series: Okabe-Ito or Paul Tol's bright scheme.
charts.scale
Map data values onto screen positions and back: linear, log, time, band and point scales, and nice domains.
charts.shape
SVG path strings for lines, areas, steps, monotone curves, bars, arcs and pie slices, identical in every language.
charts.sparkline
A sparkline's SVG path and end marker from a series, fitted into a box, with gaps left as breaks.
charts.ticks
Axis ticks: a round step (1, 2 or 5 x 10^k), the ticks on it, and calendar ticks from days to years.
collections.chunk
Split a list into consecutive batches of at most n items, in order; the last batch may be short.
collections.dedupe-by-key
Remove records that share a key value, keeping the first or the last of each, in input order.
collections.diff
Compare two lists of records by key: which were added, which removed, and which changed and in what fields.
collections.group-by-key
Group records by the value at one key, preserving input order inside each group.
collections.paginate
Slice a list into a 1-based page and report the totals an API response needs.
collections.search-text
Filter records by a case-insensitive substring match across named fields, in input order.
collections.sort-by
Stably sort records by one key, ascending or descending, with a total order across mixed types.
construction.brick-count
Bricks and mortar for a wall, openings subtracted, for UK standard 215 x 102.5 x 65 mm bricks with 10 mm joints.
construction.concrete-volume
Concrete for slabs, strip footings, pads and round columns: volume to the litre and an order rounded up to 0.1 m³.
construction.day-rate-quote
A trade quote from labour days at a day rate, materials with a markup, and VAT.
construction.materials-area
Packs of tiles, paint, plasterboard or flooring to cover an area, with waste and coats, rounded up to whole packs.
construction.payment-notice-dates
Construction Act default dates: payment due, payment notice, final date for payment and pay-less notice.
construction.retention
Retention held and released on a construction valuation: full rate, half at practical completion, none at the end.
construction.roof-pitch
Roof pitch in degrees, rafter length and roof slope area from span, rise and length.
construction.timber-length
Cutting list: which stock lengths to buy and which pieces to cut from each, allowing for saw kerf.
construction.valuation
Interim valuation: gross value to date, retention, previous payments, amount due, VAT or reverse charge, and CIS.
construction.vat-reverse-charge
Whether the UK VAT domestic reverse charge applies to a construction supply, and the invoice wording.
crypto.constant-time-equal
Compare two byte strings in time that does not depend on where they differ, for checking MACs and hashes.
crypto.hmac-sha256
HMAC-SHA256 of a message under a secret key (RFC 2104, RFC 4231), in pure code that also runs in the browser.
crypto.pbkdf2-sha256
PBKDF2 with HMAC-SHA256 (RFC 8018): derive a key from a password and salt, slowly, fast enough for a login request.
crypto.sha256
The SHA-256 digest of a byte string (FIPS 180-4), in pure code that also runs in the browser.
dates.add-business-days
Move a date forward or back by working days, skipping weekends and a caller-supplied holiday list.
dates.add-days
Shift an ISO date by a whole number of days, forwards or backwards, with exact calendar arithmetic.
dates.add-months
Add calendar months to an ISO date, clamping to the month end: 31 Jan + 1 month is 28 or 29 Feb.
dates.age
Age in whole years on a given date, with 29 February birthdays ageing on 1 March in other years.
dates.bank-holidays
UK bank and public holidays for a region and year, as published by gov.uk, including one-off holidays.
dates.business-days-between
Working days between two dates, excluding weekends and a caller-supplied holiday list.
dates.day-count-fraction
Year fraction between two dates by ACT/365F, ACT/360, 30/360, 30E/360 or ACT/ACT ISDA, as an exact fraction.
dates.day-of-week
The ISO 8601 day of the week for a date: 1 is Monday through 7 is Sunday.
dates.days-between
Calendar days from one ISO date to another, signed: negative when the second date is earlier.
dates.is-leap-year
Whether a year is a Gregorian leap year: every 4th, except centuries, except every 400th.
dates.month-boundaries
The first day, last day and length of the calendar month containing a date.
dates.overlap
Days two date ranges have in common, with the end of each range stated as inclusive or exclusive.
dates.quarter
Calendar quarter and fiscal quarter of a date, with the fiscal year and quarter date ranges, for any start month.
dates.recurrence
The next n dates of a repeating rule: monthly on a day, last weekday of the month, every k days or weeks, yearly.
dates.uk-tax-year
The UK personal tax year containing a date: 6 April to 5 April, with HMRC's label.
dates.week-number
ISO 8601 week number and week-numbering year of a date: weeks start Monday, week 1 holds the first Thursday.
education.academic-year
The academic year and term a date falls in: 1 September to 31 August by default, terms from the caller.
education.attendance-rate
Pupil attendance and absence rates in basis points, with the DfE persistent and severe absence flags.
education.cpd-hours
CPD logged against a requirement for a rolling or fixed period: minutes counted, shortfall and days left.
education.degree-classification
UK honours degree class (First, 2:1, 2:2, Third) from module marks and credits, weighted by level.
education.fee-instalments
Tuition fee instalment schedule from a total, shares and due dates, exact to the penny.
education.gpa
Grade point average on a 4.0 scale from letter grades and credit hours, weighted by credits and rounded once.
education.grade-boundaries
Grade for a mark from the caller's boundary table: inclusive lower bounds, ungraded below the lowest.
education.school-year-group
School year group from date of birth on a date, by UK nation: Reception to Year 13, P1 to S6, P1 to Year 14.
education.timetable-clash
Find timetable clashes: overlapping sessions that share a room, a teacher or a student group, in a fixed order.
education.weighted-grade
Weighted percentage across coursework and exam components, exact as a fraction, then rounded once.
encoding.hex
Bytes to lowercase hexadecimal text and back (RFC 4648 base16), strictly, identically in every language.
encoding.utf8
Text to UTF-8 bytes and strictly back (RFC 3629), so hashing and signing see the same bytes in every language.
energy.bill-calculate
Electricity or gas bill from two meter reads: energy, standing charge, Climate Change Levy and VAT.
energy.carbon-emissions
kgCO2e from kWh or litres of a fuel, using the UK government GHG conversion factors for the year.
energy.climate-change-levy
Climate Change Levy on a business supply of electricity, gas, LPG or solid fuel, at the main rate in force on the date.
energy.degree-days
Heating and cooling degree days from daily mean temperatures and a base temperature, exact to 0.1.
energy.estimate-read
Estimate a meter read for a date from the average daily consumption between two earlier reads, with rollover.
energy.gas-kwh
Convert gas meter units (cubic metres or hundreds of cubic feet) to kWh with the calorific value and 1.02264 correction.
energy.meter-advance
Units consumed between two meter reads, counting the meter rolling over past all nines once.
energy.price-cap
Ofgem energy price cap unit rate and daily standing charge for a fuel and payment method on a date (GB average).
energy.tariff-time-of-use
Cost half-hourly consumption against time-of-use rates: Economy 7 windows or Agile-style half-hourly prices.
energy.water-bill
Metered water and sewerage bill from two reads: volumetric charges, return to sewer, standing and surface water charges.
finance.accruals-prepayments
Split an invoice across accounting periods by days of service, for accruals, prepayments and deferred income.
finance.aged-debt
Aged debt report: open invoices bucketed as current, 1-30, 31-60, 61-90 and 90+ days overdue as at a date.
finance.bank-reconcile-match
Match bank statement lines to ledger entries by exact amount, a date window and reference similarity, deterministically.
finance.compound-interest
Compound interest accrued period by period in minor units, the way a statement is built.
finance.credit-note.calculate
Credit note against an original invoice, by units or by amount, with VAT at the original tax point's rates.
finance.depreciation-reducing-balance
Reducing-balance depreciation schedule at a fixed rate, writing off to the residual value in the final year.
finance.depreciation-straight-line
Straight-line depreciation schedule whose charges sum exactly to cost less residual value.
finance.early-payment-discount
Early settlement discount available on a payment date under "2/10 net 30" style terms, and the amount to pay.
finance.fx-revaluation
Unrealised foreign exchange gain or loss on foreign-currency balances revalued at a period-end rate.
finance.invoice.calculate
Calculate a complete invoice: line nets, VAT per line, totals and a VAT summary grouped by rate.
finance.invoice.line-total
Net total for one invoice line: unit price by quantity, less a discount.
finance.late-payment-interest
UK statutory late payment interest (8% over Bank Rate) and fixed compensation under the Late Payment Act 1998.
finance.ledger.journal-validate
Check a double-entry journal: debits equal credits, no zero or two-sided lines, one currency, well-formed account codes.
finance.ledger.trial-balance
Trial balance from journal lines: debit or credit balance per account, and proof that debits equal credits.
finance.margin
Profit on a sale with both the margin and the markup, so the two are never confused.
finance.markup-price
Selling price from a cost and a target margin or markup in basis points, with explicit rounding.
finance.payment-terms-due-date
Invoice due date from payment terms: net N days, end of month, N days after month end, day N of next month.
finance.tax.vat-flat-rate Unreviewed
UK VAT Flat Rate Scheme: VAT due on gross turnover at the sector's dated rate, limited cost rate and first-year 1% off.
finance.tax.vat-rate Unreviewed
Look up the VAT rate in force for a jurisdiction, category and date.
finance.uk-bank-rate
Bank of England Bank Rate (base rate) in force on a date, from the Bank's official history since 2001.
fleet.company-car-bik Unreviewed
UK company car benefit in kind: appropriate percentage by CO2 and electric range, car and fuel benefit for a tax year.
fleet.cost-per-mile
Whole-life cost per mile of a vehicle, in tenths of a penny, from depreciation, fuel, maintenance, insurance and tax.
fleet.drivers-hours Unreviewed
Check a driver's activities against GB/EU drivers' hours: breaks after 4.5h, daily, weekly and fortnightly driving.
fleet.emissions
Vehicle greenhouse gas emissions (grams CO2e) from fuel used or distance, using UK government DESNZ conversion factors.
fleet.ev-charging-cost
Cost of an electric vehicle charge from the energy added, charger efficiency and power, and time-of-use tariff windows.
fleet.fuel-cost
Fuel cost of a trip from distance, fuel economy (UK or US mpg, or L/100km) and price per litre, exactly.
fleet.service-due
Next vehicle service by months or miles, whichever comes first, projecting the mileage date, with an overdue flag.
fleet.vehicle-depreciation
A vehicle's current value from its cost, age and mileage, on retention curves the caller supplies, exactly.
form.character-count
The GOV.UK character count message for a text box: characters or words left or over a limit, with a threshold.
form.date-parts
Check a date typed into day, month and year boxes, with GOV.UK's error messages and the boxes to mark in error.
form.state TypeScript only
A form's state as a pure reducer: values, touched fields, validator errors and the submit, for useReducer.
geo.bounding-box
Latitude/longitude bounding box that contains every point within a distance of a centre point.
geo.distance
Great-circle distance in metres between two latitude/longitude points (haversine), to the millimetre.
geo.point-in-polygon
Whether a latitude/longitude point lies inside a polygon (ray casting; the boundary counts as inside).
health.age-in-months Unreviewed
Age in completed months and days on a given date, for paediatric charts and doses; month ends handled like birthdays.
health.appointment-slots Unreviewed
Bookable appointment slots from clinic sessions, a slot length, breaks and existing bookings.
health.bmi Unreviewed
Adult body mass index (kg/m², 1 decimal place) and its NICE/WHO weight category.
health.bsa Unreviewed
Body surface area in m² by the Mosteller and the DuBois & DuBois formulas, to 2 decimal places.
health.egfr Unreviewed
eGFR in mL/min/1.73 m² by the race-free CKD-EPI 2021 creatinine equation, from creatinine in µmol/L or mg/dL.
health.gestational-age Unreviewed
Gestational age (weeks+days) and estimated due date from the last menstrual period by Naegele's rule, cycle-adjusted.
health.news2 Unreviewed
NEWS2 early warning score from one set of observations: parameter scores, aggregate and RCP clinical risk band.
health.nhs-number-format Unreviewed
Display an NHS number in the 3-3-4 format ("943 476 5919") after checking its modulus 11 check digit.
health.qrisk-inputs-validate Unreviewed
Check a QRISK3 cardiovascular risk input set against the calculator's published ranges; does not compute risk.
health.waiting-time Unreviewed
NHS England referral-to-treatment (RTT) wait in days and weekly bands, with the 18-week breach flag.
hospitality.allergen-matrix Unreviewed
Which of the 14 UK major allergens a dish contains or may contain, from its ingredients' declared allergens.
hospitality.cancellation-charge
Cancellation fee for a booking from a policy of notice bands and the days of notice given.
hospitality.gross-profit-menu
Menu gross profit (GP%) on the VAT-exclusive price, and the menu price that reaches a target GP.
hospitality.occupancy-adr-revpar
Hotel occupancy, average daily rate (ADR) and revenue per available room (RevPAR) for a period.
hospitality.recipe-cost
Cost a recipe and each portion from ingredient quantities, pack sizes and pack prices, allowing for trim and waste.
hospitality.recipe-scale
Scale a recipe to a new number of portions, tidying metric units (g to kg, mL to L) and rounding to kitchen precision.
hospitality.room-rate
Price a hotel stay night by night from the caller's seasonal, day-of-week rate table, less any length-of-stay discount.
hospitality.service-charge
A discretionary service charge on a bill's eligible lines, as a basis-point rate with explicit rounding.
hospitality.tourist-tax
Visitor levy (tourist tax) on an overnight stay: Edinburgh's 5%, Cardiff's per person per night, or a caller's own rule.
hospitality.tronc-allocation
Share a tips pool (tronc) between staff by hours worked, points, or hours times points, exactly to the penny.
hr.absence-bradford-factor
Bradford factor for a set of absence spells: spells squared times total days, which weights frequent short absences.
hr.length-of-service
Continuous service between two dates in completed years, months and days, counting both end dates.