Expand an RRULE recurrence rule into its occurrence datetimes, with a human-readable description.

Internal rate of return (per period) of a series of cash flows, solved with a bounded bisection. Requires at least one positive and one negative flow; flows with no sign change or no bracketable root are rejected as a clean 400.

The warnings the Deutscher Wetterdienst has actually issued for the warn cell containing the coordinate, in German and English, with severity, urgency, certainty and an explicit effective/onset/expires window plus whether the warning is active right now.

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

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.

Spell text using the NATO/ICAO phonetic alphabet (A→Alfa, B→Bravo, …), including digits and spaces (→Space). Characters with no phonetic spelling are clean 400s.

TraceFast knowledge graph: the relations an address holds now — which implementation a proxy points at, which beacon it reads, who administers it, where an account has delegated, which lending market lists a token — as the subject (`direction=subject`: what it points at, default) or as the object (`direction=object`: who points at it). Path: address. Query: direction, attributeId, limit, cursor (see docs). Docs: https://docs.tracefast.xyz/api/address-relations.md

Read an ERC-20 balance with symbol, decimals and a formatted amount — one call, no ABI work, live from Base mainnet, for a fraction of a cent. No API key, no account — a wallet is the only requirement, and you are charged only if the read succeeds. Plain unsigned data; the attested version of chain reads is /v1/oracle/onchain. Answers are read at the moment of the call and stamped with the block they came from where applicable.

Generate a random Luhn-valid TEST card number for the given network (default Visa). For testing only — these are not issued cards and cannot be charged. The response is always flagged `test:true`.

TraceFast knowledge graph: the relations an address was the subject of at the end of one block — which implementation a proxy pointed at, which beacon it read, who administered it, where an account had delegated — each with the window it held for. Path address: The address, `0x`-prefixed, 40 hex characters, any case. Query block: The block to answer about. Docs: https://docs.tracefast.xyz/api/address-relations-at-block.md

Decode international Morse code back into text. Letters are separated by whitespace and words by "/". Unknown Morse sequences are clean 400s.

Parse a semantic version into major/minor/patch, prerelease and build metadata.

Compute sunrise, sunset, solar noon and day length for a latitude/longitude (east-positive) and date, using the NOAA sunrise equation. All times are UTC ISO-8601. Locations in polar day or night return null rise/set with a `polar` flag — a successful result, not an error.

Summarise a text's difficulty as a single consensus US grade level (averaging the five grade formulas), plus the Flesch Reading Ease, a plain-language difficulty band and an approximate age range.

Parse, validate and format a phone number — E.164/national/international/RFC 3966, region and line type (syntactic validation, no carrier lookup).

Encode text to HTML entities so it can be safely embedded in markup. By default uses hex numeric references; set useNamedReferences for named entities (&, ©) or encodeEverything to encode every character.

Recent contract deploys with labels and per-hour history (?limit=200)

DNS and list based verification. Never claims that a mailbox exists without evidence: without an SMTP probe the verdict for a routable address is "unknown", not "valid".

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

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.