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.

Normalise a postal code's casing and whitespace (uppercase, collapse runs of spaces) and report whether the normalised form is valid for the country.

Break a braille string into its cells and the raised-dot numbers (1–8) of each cell.

Given a reaction and a known amount (moles or grams) of one species, compute the amount of a target species. The equation is balanced automatically.

Given a reaction and the supplied amount of every reactant, identify the limiting reagent and compute leftover reactant and theoretical product yields.

Parse dice notation such as "3d6+2", "4d6kh3" (keep highest 3) or "2d20dl1" (drop lowest 1) into structured terms. Malformed notation is a clean 400.

Shift a non-negative integer left or right by `amount` bits. A right shift is logical (fills with zeros). A left shift grows freely unless a `width` is given, in which case the result is masked to that width and the input must fit it. Returns decimal, hex and binary.

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.

Resolve an emoji by its shortcode (e.g. "smile" or ":smile:") or exact name. Provide exactly one field. Returns the emoji, its metadata and code points.

Rebuild a nested object from a single-level object whose keys are delimited paths (default delimiter `.`) — the inverse of flatten. Requires a flat object.

Roll dice notation with a cryptographically secure RNG, optionally repeated. Returns per-die rolls, the kept dice and the total for each roll.

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.

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.

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.

Balance an equation such as "H2 + O2 -> H2O" into the smallest whole-number coefficients using exact rational linear algebra. Equations that cannot be balanced with positive coefficients are clean 400s.

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.

Build the flag emoji for an ISO 3166-1 alpha-2 country code from its regional-indicator symbols (e.g. "US" → 🇺🇸). Non two-letter codes are clean 400s.

Return the validation regular expression (source and flags) used for a country's postal codes.

Look up a country by its ISO 3166-1 alpha-2 code, alpha-3 code, numeric code or English name. Provide exactly one field. Returns all codes plus the UN region.

Inspect a non-negative integer's bit structure: bit length, set-bit count (population count), trailing-zero count, power-of-two test, and hex/binary representations. An optional width zero-pads the binary form.