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Validate a GTIN barcode number — EAN-8, UPC-A (12), EAN-13 or GTIN-14 — by the standard mod-10 check digit. Length selects the scheme.

Classify a User-Agent by device form factor and return convenience booleans (isBot, isMobile, isTablet, isDesktop, isTouchCapable) for routing decisions.

Resolve a relative or absolute reference against a base URL, following RFC 3986 reference resolution (e.g. base 'https://a.com/x/y' + ref '../z' → 'https://a.com/z'). The base must itself be a valid absolute URL, else a clean 400.

Add, subtract, multiply or divide two fractions and return the exact, fully-reduced result. All computation is done in BigInt so there is no floating-point error. Dividing by a zero fraction is a clean 400.

Count syllables per word and in total across the text.

Convert decimal lat/lon to a Military Grid Reference System (MGRS) string on WGS84. Precision is the number of digits per axis (1–5; 5 = 1-metre resolution, default 5).

Parse an .ics document into structured calendar events (summary, times, location, RRULE, attendees).

Distance and initial bearing between two coordinates.

Split an identifier or phrase into words and render it in every common case — camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE, dot.case, path/case, Title Case and Sentence case. Handles acronyms (HTMLParser → html parser).

Compute the exact probability distribution of a dice notation — mean, variance, standard deviation, min/max and the full probability mass function — with no sampling. Notations whose outcome range is too large for exact computation are clean 400s.

Apply a Unicode normalisation form (NFC, NFD, NFKC or NFKD) to a string. Reports whether the text changed and its length in UTF-16 code units and code points.

Fuzzy-search countries, currencies and languages by name or code. Scope with `registry` (defaults to all). Matches are ranked exact-code/name → prefix → substring.

Encode text into international (ITU) Morse code. Letters are separated by spaces and words by "/". Supports A-Z, 0-9 and common punctuation; unsupported characters are clean 400s.

Circularly rotate a non-negative integer left or right within an explicit bit width (bits shifted off one end reappear at the other). The value must fit in `width` bits. Returns decimal, hex and binary.

Validate a 15-digit mobile device IMEI by its Luhn check digit. Spaces and hyphens are ignored.

Return the singular form of an English word (handles irregulars — people → person, mice → mouse).

Reduce a fraction to lowest terms and describe it: numerator/denominator (denominator normalized positive), sign, whether it is an integer, and a mixed-number form when improper. A zero denominator is a clean 400.

List a country's holidays for a calendar year (optionally by state/region, language and type).

Parse a coordinate string into decimal lat/lon. Accepts a plain decimal pair ('40.4462, -79.9822') or DMS with hemisphere letters ('40°26'46"N 79°58'56"W'). Anything unrecognized is a clean 400.

List the supported units and their metadata (abbreviation, measure, system, singular/plural names), optionally filtered to a single measure — a discovery endpoint for choosing valid `from`/`to` values.

Reformat a MAC address into the requested notation (colon, hyphen, Cisco dot or bare) and case (lower default or upper).

Bitwise AND across two or more non-negative integers (given as decimal strings, evaluated as arbitrary-precision BigInt). Returns the result in decimal, hex and binary.

Convert decimal lat/lon to a UTM coordinate (zone, latitude band, hemisphere, easting, northing) on WGS84, including the Norway/Svalbard zone exceptions. Defined for latitudes -80..84.

Remove all HTML tags, returning the plain text content. Entities are decoded to real characters by default (set decodeEntities=false to keep them encoded).