Other

Mask a card number for display, keeping the first six and last four digits (the PCI-permitted maximum) and replacing the rest with a mask character (default `*`).

Evaluate whether a mathematical research branch should continue, revise, abstain, or escalate.

Validate a Latvian VAT (PVN) number against the official VAT-payers register. Validity means the number has a currently active entry in the register.

Compute the WCAG 2.1 contrast ratio between two colors and whether it passes AA/AAA.

Find the nearest CSS named color to a given color, by perceptual distance.

Validate an ISBN-10 (mod-11, trailing X allowed) or ISBN-13 (GTIN mod-10) book number. Length after removing spaces/hyphens selects the scheme.

Test whether an IP address falls within a CIDR block. A well-formed address of a different family (or simply outside the block) returns contains=false — not an error.

Validate a number by the Luhn (mod-10) algorithm — the scheme behind credit/debit card numbers and many IDs. Spaces and hyphens are ignored. A mismatched check digit is a successful { valid: false }.

Add or subtract from a timecode, either another timecode (b) or a raw frame count (frames), at a given frame rate. Uses frame-exact SMPTE math (including drop-frame). A result below zero is rejected as a clean 400.

Return the ISO weekday (1=Monday..7=Sunday) and its name for a Gregorian date.

Name the interval between two notes (`to` at or above `from`) — its size in semitones, its diatonic number and its quality (perfect/major/minor/augmented/diminished). Correct spelling matters: C→F# is an augmented fourth, C→Gb a diminished fifth.

Build a chord from a root note and quality (major, minor, dim, aug, maj7, min7, dom7, dim7, half-dim7, sus2, sus4, maj6, min6). Notes are spelled by stacked thirds (C dom7 → C E G Bb). Returns the note names, MIDI numbers and semitone intervals.

Jaccard similarity index in [0,1] — the size of the intersection over the union of the two strings' character-bigram sets.

Prime-factorize a positive integer (≤ 10^15 so the computation is always fast). Returns the prime factors with exponents, the divisor count, and whether n is prime.

Compute the molar mass (g/mol) of a chemical formula. Supports nested parentheses and brackets, element multipliers, and hydrate dot notation with coefficients (e.g. "Ca(OH)2", "CuSO4·5H2O", "K4[Fe(CN)6]"). Returns the total mass and the per-element composition with mass fraction percentages.

Greatest common divisor of two or more non-negative integers (arbitrary precision).

Compare two semantic versions and report which is greater (precedence-aware).

Canonicalize a URL: WHATWG parsing already lowercases the host, resolves dot-segments and drops default ports; on top of that, query parameters are sorted by default and you can optionally drop the fragment or a trailing slash. Returns the normalized URL and whether it changed.

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.

Detect the issuing network/brand (Visa, Mastercard, American Express, Discover, Diners Club, JCB, UnionPay, Maestro) from the card's IIN prefix, with the network's valid lengths. Returns `network:null` for an unrecognized prefix.

Format a card number into the conventional display groups for its network (4-6-5 for Amex, 4-6-4 for 14-digit Diners, otherwise groups of four).

Binomial coefficient nCr = n!/(r!(n-r)!), the number of unordered r-subsets of n. Requires r ≤ n and min(r, n-r) ≤ 10000.

Euclidean, Manhattan and Chebyshev distance between two 2-D points.

Split an amount into parts using integer minor-unit math so the shares always sum back to the exact original — no rounding drift. Pass parts for an even split, or ratios for a weighted one (e.g. [1,1,1] splits $100 into 33.34/33.33/33.33). The leftover minor units go to the largest fractional remainders.

Report the properties of a MAC address encoded in its first octet: unicast vs multicast (I/G bit), universal vs locally-administered (U/L bit), the broadcast address, and — for EUI-48 — the OUI and NIC portions.

Format a non-negative integer as an ordinal — both the suffixed form (21st) and the ordinal words (twenty-first).

Generate one or more uniformly-distributed random integers in an inclusive [min, max] range.

Scores JSONL rows using fixed rules and adds _quality. Detects some PII and bad-word patterns; optional redaction and score filtering. Detection is incomplete and can produce false positives. No AI.

Signed integrity, provenance and freshness receipt for AI-agent JSON

Computes the Levenshtein edit distance and a similarity percentage between two strings.

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