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
money.amount
A currency-tagged monetary amount held in integer minor units.
finance.proration
Split an amount into the part used and the part unused over a billing period, losing nothing.
validation.uk-postcode
Validate a UK postcode and normalise it to canonical upper case with one space before the inward code.
agri.fertiliser-application
Fertiliser product rate (kg/ha and total) to meet N, P2O5 and K2O targets from its analysis, limiting nutrient first.
agri.field-area
Field area in square metres, hectares and acres from a boundary polygon of latitude/longitude points.
money.split-even
Split an amount into n near-equal parts that add back up to exactly the whole.
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.
net.ipv6
Parse IPv6 addresses and write them in RFC 5952 canonical form: lower-case, zeros compressed, IPv4 embedded.
payroll.minimum-wage-check Unreviewed
Check pay for a pay reference period against the minimum or living wage for age and apprenticeship.
telecoms.call-rating
Rate a call from a rate deck: longest-prefix destination match, billing increments, connection fee and minimum charge.
agri.gross-margin
Enterprise gross margin (output less variable costs), in total and per hectare or per head, in exact money.
auth.jwt
Sign, verify and decode HS256 JSON Web Tokens (RFC 7519): signature, algorithm and exp/nbf/iat checked with leeway.
charts.bar-chart
Complete bar chart geometry as data, grouped or stacked: plot area, axes, gridlines, bar rectangles, colours, legend.
charts.downsample
Reduce a long series to a few points that keep its visual shape, by Largest-Triangle-Three-Buckets (LTTB).
charts.stack
Stack several series for stacked bars and areas: on zero, normalised to 100%, or diverging around zero.
encoding.base64
Bytes to base64 and base64url text and back (RFC 4648), with strict decoding, identically in every language.
encoding.hex
Bytes to lowercase hexadecimal text and back (RFC 4648 base16), strictly, identically in every language.
energy.tariff-time-of-use
Cost half-hourly consumption against time-of-use rates: Economy 7 windows or Agile-style half-hourly prices.
finance.fx-revaluation
Unrealised foreign exchange gain or loss on foreign-currency balances revalued at a period-end rate.
finance.tax.add-vat Unreviewed
Add VAT to a net 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).
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).
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.
hospitality.gross-profit-menu
Menu gross profit (GP%) on the VAT-exclusive price, and the menu price that reaches a target GP.
inventory.eoq
Economic order quantity (Harris/Wilson): the order size that minimises ordering plus holding cost, in whole units.
logistics.freight-rate
Freight charge from a carrier's dated weight-break tariff for a zone, with the fuel surcharge in force on the ship date.
math.big-integer
Exact integer arithmetic of any size, on decimal strings, for powers and products that overflow 64 bits.
math.pow
base to the power exponent from + - * / only, exact by squaring for whole exponents, identical in every language.
math.sin-cos
Sine and cosine of an angle in radians from + - * / only, so every language returns the same doubles.
monitor.error-budget
How much of an SLO's error budget is allowed, used and left, from good and bad event counts or seconds.
monitor.rollup
Aggregate a metric series into fixed time buckets (count, min, max, avg, sum, last), empty buckets included.
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).
react.form.form-field React ^19 · TypeScript only
Wire a label, hint and error message to one form control by id, the accessible way (GOV.UK form group pattern).
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.
stats.moving-average
Simple or exponential moving average over a series, one value per full window, rounded to stated decimals.
validation.bic
Check the format of a SWIFT/BIC code (8 or 11 characters) and split it into its parts.
validation.email
Is this a plausible email address? A documented, pragmatic subset of RFC 5322, not the full grammar.
validation.lei
Check a 20-character Legal Entity Identifier against its ISO 17442 / ISO 7064 MOD 97-10 check digits.
agri.feed-ration
Ration costing and dry matter intake from each feed's fresh weight, DM % and price per tonne, in exact money.
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.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.access-token
Issue an API's HS256 access token, read one from an Authorization header, and refuse revoked or superseded ones.
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.fees-cap
Apply a monthly fee cap to a list of account charges: charge up to the cap, waive the rest.
charity.donation-matching
Employer match on a donation: a ratio in basis points, limited by a per-donor cap and a programme budget.
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.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.reclaim-batch
Gift Aid claim totals for a period from donation records: donor lines, aggregated small gifts, tax due.
charts.contrast
WCAG 2.x contrast ratio between two colours, and which text colour reads best on a background.
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.
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.sort-by
Stably sort records by one key, ascending or descending, with a total order across mixed types.
construction.cis-deduction
Construction Industry Scheme deduction (0, 20 or 30%) on the labour part of a subcontractor payment.
construction.vat-reverse-charge
Whether the UK VAT domestic reverse charge applies to a construction supply, and the invoice wording.
dates.age
Age in whole years on a given date, with 29 February birthdays ageing on 1 March in other years.
dates.quarter
Calendar quarter and fiscal quarter of a date, with the fiscal year and quarter date ranges, for any start month.
dates.uk-tax-year
The UK personal tax year containing a date: 6 April to 5 April, with HMRC's label.
education.academic-year
The academic year and term a date falls in: 1 September to 31 August by default, terms from the caller.
education.student-loan-repayment
A graduate's student or postgraduate loan repayment for a tax year, as Self Assessment works it out.
education.timetable-clash
Find timetable clashes: overlapping sessions that share a room, a teacher or a student group, in a fixed order.
encoding.utf8
Text to UTF-8 bytes and strictly back (RFC 3629), so hashing and signing see the same bytes in every language.
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.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.solar-generation
Estimated annual solar PV generation by the MCS method: kWp x Kk x shade factor, per array and in total.
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.tax.remove-vat Unreviewed
Extract the VAT already included in a gross amount, using the rate in force on the date of supply.
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.cost-per-mile
Whole-life cost per mile of a vehicle, in tenths of a penny, from depreciation, fuel, maintenance, insurance and tax.
fleet.fuel-cost
Fuel cost of a trip from distance, fuel economy (UK or US mpg, or L/100km) and price per litre, exactly.
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).
hospitality.recipe-cost
Cost a recipe and each portion from ingredient quantities, pack sizes and pack prices, allowing for trim and waste.
inventory.abc-classification
ABC classes by annual consumption value (Pareto), with configurable cut-offs such as 80/15/5 and deterministic ties.
inventory.reorder-point
Reorder point: demand over the supplier lead time, rounded up to whole units, plus safety stock.
invest.rebalance Unreviewed
Whole-unit buy and sell trades that bring a portfolio back to target weights, skipping trades below a minimum size.
lending.affordability Unreviewed
Debt-to-income and a stressed-rate affordability test for a proposed loan's monthly repayment.
lending.amortisation-schedule Unreviewed
Repayment schedule for a level-payment loan: interest, principal and balance per period, ending at exactly zero.
logistics.demurrage
Demurrage or detention charge for a container: free days, then a tiered daily rate from the carrier's tariff.
logistics.route-distance
Total great-circle distance of an ordered list of stops, leg by leg, optionally back to the start, to the millimetre.
manufacturing.batch-size
Economic batch quantity: the EOQ for a batch made at a finite production rate, in whole units.
manufacturing.bom-explode
Explode a multi-level bill of materials into exact total quantities per component, with scrap and cycle checks.
math.basis-points
Convert a rate between percent, basis points and a plain ratio exactly, as decimal text or integer basis points.
math.integer-sqrt
Exact integer square root: the largest whole number whose square does not exceed n.
math.round-div
Integer division with an explicit rounding mode, for money arithmetic that must not drift.
math.round-float
Round a float half away from zero to 0-12 decimal places, identically in TypeScript, Python and Rust.
money.convert
Convert an amount to another currency at a supplied exact rate, with an explicit rounding mode.
money.currency-digits
How many decimal places a currency's minor unit has, from the ISO 4217 list.
monitor.mttr
MTTR, MTBF, downtime and incident counts for a reporting window, from a list of incidents.
monitor.uptime
Time-weighted uptime of a target over a window from its checks, with gaps longer than a limit counted as unknown.
net.ipv4
Parse, format and check dotted-quad IPv4 addresses, refusing leading zeros, octal, hex and short forms.
payroll.holiday-pay-accrual Unreviewed
UK holiday pay: 12.07% rolled-up holiday pay, or a week's pay averaged over the last 52 paid weeks.
payroll.national-insurance Unreviewed
Employee and employer Class 1 National Insurance for one payment by category letter, exact percentage method.
payroll.net-to-gross Unreviewed
The gross pay that gives at least a target net pay in one UK pay period, found by a deterministic search.
payroll.overtime Unreviewed
Pay for the time worked in a period split into multiplier bands: basic, time and a half after 40 hours, double time.
payroll.student-loan Unreviewed
Student loan or postgraduate loan deduction from one period's pay, by plan, rounded down to whole pounds.
payroll.tax-code-parse Unreviewed
Parse a UK PAYE tax code (1257L, K475, BR, D0, NT, 0T, S and C prefixes, W1/M1/X) into its allowance and flags.
property.service-charge-apportion Unreviewed
Apportion a service charge across units by lease fraction, floor area or fixed percentage, exact to the penny.
react.form.checkbox-group React ^19 · TypeScript only
A question answered by ticking any of several checkboxes, with item hints and an exclusive "None" (GOV.UK checkboxes).
react.form.styles React ^19 · TypeScript only
An optional stylesheet for the react.form elements' caps-* classes, themed by --caps-form-* custom properties.
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.
retail.shipping-rate
Delivery charge from a dated rate table by service, zone, chargeable weight and size, with a free-over threshold.
todo.due-label
The short English label shown next to a todo: "2 days overdue", "Due today", "Due tomorrow", "Due Fri 2 Oct".
units.convert
Convert length, mass, area, volume, temperature and energy between units, exactly, as decimal text.
validation.iban
Check an IBAN against the ISO 13616 mod-97-10 checksum and the registered length for its country.
validation.uk-vat-number
Check a UK VAT registration number against HMRC's mod-97 checksum, including the post-2010 9755 variant.
validation.vin
Check a 17-character vehicle identification number and its check digit; enforced for North American VINs.
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.stocking-rate
Stocking rate: livestock units and LU per hectare from animal numbers, by a published LU coefficient table.
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.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.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.fundraising-ratio
Cost to raise £1 and charitable spend ratio for a charity, in exact basis points.
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.color
Hex colours to RGB and back, and sRGB channels to linear light and back, identically in every language.
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.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.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.
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.
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.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.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.week-number
ISO 8601 week number and week-numbering year of a date: weeks start Monday, week 1 holds the first Thursday.
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.weighted-grade
Weighted percentage across coursework and exam components, exact as a fraction, then rounded once.
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.gas-kwh
Convert gas meter units (cubic metres or hundreds of cubic feet) to kWh with the calorific value and 1.02264 correction.
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.invoice.calculate
Calculate a complete invoice: line nets, VAT per line, totals and a VAT summary grouped by rate.