Fuzzy-search emoji by name, shortcode or keyword tag, ranked exact → prefix → substring.

Least common multiple of two or more positive integers (arbitrary precision).

Decode HTML entities (named, decimal and hex numeric references) back into plain text.

Estimate password strength: score, guesses, crack-time and feedback. Never stored.

Split YAML front-matter from a document — returns the parsed metadata object and the remaining content body. Malformed YAML is rejected as a clean 400.

Encode a word with the classic Soundex algorithm (letter + 3 digits) for phonetic matching of names.

Encode a word with Double Metaphone, returning a primary and a secondary code to capture alternate pronunciations (useful for non-English names).

Look up an active ISO 4217 currency by its alphabetic code or numeric code. Provide exactly one field. Returns the code, numeric code, name and number of minor units (decimal places).

Ordinary-least-squares linear regression of y on x: slope, intercept, correlation r and coefficient of determination r². Pass predictAt to also evaluate the fitted line at a given x. Rejected as a clean 400 if lengths differ or x has zero variance.

Decode a JSON Web Token WITHOUT verifying its signature and return the header, payload and signature. A structurally malformed token is rejected before payment. Never trust a decoded payload you have not verified.

Encode a word with the Metaphone algorithm — more accurate than Soundex for English pronunciation.

Generate a random string of a given length from a named charset (alphanumeric, alpha, lower, upper, numeric, hex, base58) or a custom alphabet. Unbiased character selection.

Verify a JSON Web Token's signature and claims against a shared secret (HS*) or a PEM public key (RS/ES/PS). Returns { valid, payload } on success or { valid: false, reason } for a bad signature, expired/not-yet-active token, or a failed issuer/audience/subject check. Pass `algorithms` to pin the accepted signing algorithms and prevent algorithm-confusion attacks.

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

Parse a document (json, json5, jsonc, yaml, xml, csv, tsv, toml, ndjson, ini, env, properties, plist or querystring) and validate it against a JSON Schema. Returns whether it is valid and a list of precise, path-tagged errors. Malformed input or an invalid schema is rejected before payment.

Validate a ULID and extract its embedded timestamp and time/random components.

Infer a JSON Schema (draft-07) from a sample document in any supported format. Types are inferred, present keys are marked required, and heterogeneous array item schemas are merged. The result validates out of the box with /v1/validate.

Parse a document (in any format) and re-emit it in the RFC 8785 JSON Canonicalization Scheme form — sorted keys, canonical number/string formatting — plus the SHA-256 of the canonical bytes for stable hashing, signing and dedup.

Convert a decimal string to an exact reduced fraction. For a repeating decimal, set repeat to the number of trailing fractional digits that repeat (e.g. value='0.1666', repeat=1 → 1/6; value='0.3', repeat=1 → 1/3). A non-numeric value is a clean 400.

Look up a physical constant by its key (e.g. "speed-of-light"), symbol (e.g. "c") or exact name. Returns the CODATA 2018 recommended value, unit, relative standard uncertainty (0 for values that are exact by SI definition) and category.