We count page visits with Google Analytics to see which pages are read. Nothing is stored until you accept, and we never store search queries. Privacy.
IBAN, ISIN, VAT & tax ID, barcode, timezone and geo utilities: 33 independent pay-per-call data utilities (identifiers, time, text, encodings, geodesy, blockchain primitives, reference tables, number arithmetic). $0.05 per call, payable over x402 (USDC on Base, eip155:8453). No account, no API key.…
Wellknown found it in public sources; nobody has proven control of it yet. Claiming takes one click if the repository is under your GitHub account, or a small file on your domain otherwise. Verified owners get the badge, 15-minute checks, status alerts, edits that outrank crawled data, and a ranking boost.
Agents can do it too: POST https://wellknown.network/api/v1/claims with {"agent":"duo-leads-duo-data-utilities","method":"well_known_file"} — machine-readable steps at claim.json, guide at /docs/claim.
Everything here was measured by our prober or read from a registry. Nothing is self-reported.
30-day availability67/67 checks ok
30 days agotoday
Endpoints
https://api.duoleads.coma2a · auth: none · checked on a schedule
Registry facts
Not distributed through a package registry we index.
when
check
result
http
latency
detail
2 h ago
a2a card
ok
200
30 ms
card: Duo Data Utilities · 33 skills
8 h ago
a2a card
ok
200
72 ms
card: Duo Data Utilities · 33 skills
15 h ago
a2a card
ok
200
54 ms
card: Duo Data Utilities · 33 skills
21 h ago
a2a card
ok
200
41 ms
card: Duo Data Utilities · 33 skills
27 h ago
a2a card
ok
200
21 ms
card: Duo Data Utilities · 33 skills
34 h ago
a2a card
ok
200
53 ms
card: Duo Data Utilities · 33 skills
2 d ago
a2a card
ok
200
23 ms
card: Duo Data Utilities · 33 skills
2 d ago
a2a card
ok
200
32 ms
card: Duo Data Utilities · 33 skills
2 d ago
a2a card
ok
200
61 ms
card: Duo Data Utilities · 33 skills
3 d ago
a2a card
ok
200
280 ms
card: Duo Data Utilities · 33 skills
Declared by sources
What the publisher says
Attributed to the source that supplied each field. Treated as claims, not facts.
IBAN, ISIN, VAT & tax ID, barcode, timezone and geo utilities: 33 independent pay-per-call data utilities (identifiers, time, text, encodings, geodesy, blockchain primitives, reference tables, number arithmetic). $0.05 per call, payable over x402 (USDC on Base, eip155:8453). No account, no API key. A2A: JSON-RPC at https://api.duoleads.com/a2a; send a DataPart {"skill": "<skill id>", "params": {...}}; skill execution is paid through the a2a-x402 extension. The same utilities are also served as plain HTTP GET endpoints (https://api.duoleads.com/openapi.json) and as MCP tools over Streamable HTTP at https://api.duoleads.com/mcp (tools/list free, tools/call paid).
VAT, tax ID and national ID validator: 23 countries, checksum only (VAT formats BE, DE, FR, IT, PL, AT, CH, IE) — VAT, tax ID and national ID validator: check a national identity, tax or company registration number against its country's official checksum rule. Covers 23 countries including NL BSN, ES NIF/NIE/CIF, IT codice fiscale, FR SIREN/SIRET, DE Steuer-ID, BE/PL/CZ national numbers, SE/NO/DK/FI personal numbers, BR CPF/CNPJ, AU ABN/TFN, UK NINo, IE PPS, US NPI/EIN. Structure and check digit only, no registry lookup; the number is never stored (logs keep only its length and character types). Price: $0.…
GTIN barcode validator: EAN-13, UPC-A (GTIN-12), GTIN-8/14, GLN and SSCC check digits — GTIN barcode validator: validate and convert GS1 identifiers: GTIN-8, GTIN-12 (UPC-A), GTIN-13 (EAN-13), GTIN-14, GLN and SSCC. Returns the check-digit verdict, the computed correct check digit, the GTIN-14 form with its indicator digit, and conversion between GTIN-8, -12, -13 and -14. No company-prefix split is returned: GS1's prefix-length table is no longer public data. Also computes a missing check digit from a partial code. Structure only, no product database. Price: $0.05 per call. Also G…
ISIN validator plus CUSIP, SEDOL and FIGI check-digit validation; builds an ISIN from an NSIN — ISIN validator plus CUSIP, SEDOL and FIGI check digits: validate the check digit of a financial security identifier (ISIN per ISO 6166). Returns the verdict, the computed correct check character, and for an ISIN the issuing country prefix and the embedded NSIN. Also builds an ISIN from a country code plus a 9-character NSIN. Format and checksum only, no security master lookup. Price: $0.05 per call. Also GET /v1/id/security.
IBAN validator: length, mod-97 check digits, bank/branch/account breakdown (89 countries) — IBAN validator: validate an IBAN's length for its country, permitted character classes per field, and the ISO 7064 mod-97-10 check digits. Returns the verdict with a specific failure reason, the electronic and print formats, and the decomposed bank code, branch code and account number according to that country's registered layout. Covers the 89 countries of the SWIFT IBAN registry. Structure and checksum only, it does not confirm the account exists. Price: $0.05 per call. Also GET /v1/id/iban.
IBAN generator: build an IBAN from country and BBAN or bank/branch/account, computing check digits — IBAN generator: construct an IBAN from a country code and the domestic account parts, computing the ISO 7064 mod-97-10 check digits. Takes a single BBAN string or named parts (bank code, branch code, account number); digit fields are left-padded with zeros to the country's registered widths. Returns the IBAN in electronic and print formats with its bank, branch and account parts. Covers the 89 SWIFT registry countries. Named parts work only where they span the whole BBAN; else pass the BBAN. Pr…
kind ← A2A Agent Card
name ← A2A Agent Card
summary ← A2A Agent Card
version ← A2A Agent Card
description ← A2A Agent Card
homepageUrl ← A2A Agent Card
publisherUrl ← A2A Agent Card
publisherName ← A2A Agent Card
Derived by Wellknown
Capabilities
Mapped onto the structured taxonomy from declared text and observed tool names. Confidence shown for derived entries.
4 d ago · declared · summary → "IBAN, ISIN, VAT & tax ID, barcode, timezone and geo utilities: 33 independent pay-per-call data utilities (identifiers,
4 d ago · declared · description → "IBAN, ISIN, VAT & tax ID, barcode, timezone and geo utilities: 33 independent pay-per-call data utilities (identifiers,
18 d ago · declared · publisherName → "Duo Leads"
18 d ago · declared · publisherUrl → "https://api.duoleads.com"
18 d ago · declared · summary → "33 independent pay-per-call data utilities (identifiers, time, text, encodings, geodesy, blockchain primitives, referen
18 d ago · declared · version → "1.0.0"
18 d ago · declared · protocols → ["a2a"]
18 d ago · declared · homepageUrl → "https://api.duoleads.com/docs"
18 d ago · declared · description → "33 independent pay-per-call data utilities (identifiers, time, text, encodings, geodesy, blockchain primitives, referen
Timezone converter: instant to local time in an IANA time zone and back, with UTC offset and DST state — Timezone converter: convert an instant to wall-clock time in a named IANA time zone, or a wall-clock time in a zone back to an instant. Returns the local date and time, the UTC offset in ±HH:MM and seconds, the zone abbreviation, whether DST is in effect, the ISO week date, and the day of year. Handles the ambiguous and skipped local times at DST boundaries explicitly rather than guessing. Price: $0.05 per call. Also GET /v1/time/zone.
DST transitions: next daylight-saving time changes for an IANA time zone — DST transitions: list the daylight-saving time changes for an IANA time zone over a date range: the exact instant of each shift, the offset before and after, and whether local clocks jump forward or back. Returns the current offset and DST state, and the next transition from a given instant. Zones without DST return an empty transition list rather than an error. Price: $0.05 per call. Also GET /v1/time/dst.
Business days calculator: add or count working days with your weekend mask and holiday list — Business days calculator with a caller-supplied calendar: add or subtract N working days from a date, or count the working days between two dates. The weekend is a weekday mask (Friday-Saturday and Sunday-only weeks work) and holidays are an explicit date list, so nothing depends on a stale holiday table. Returns the result date, the day count and the skipped dates with reasons. The skipped list is capped at 1,000 entries (skipped_truncated flags it); skipped_total is always exact. Price: $0.05…
RRULE expander: RFC 5545 recurrence rule to concrete occurrence dates — RRULE expander: expand an RFC 5545 recurrence rule into concrete occurrence timestamps. Accepts an RRULE string with DTSTART, an IANA time zone, and optional EXDATE and RDATE lists, and returns up to 200 occurrences as both local wall-clock times and UTC instants. Supports FREQ, INTERVAL, COUNT, UNTIL, BYDAY, BYMONTHDAY, BYMONTH, BYSETPOS and WKST. Occurrences moved by a DST gap carry gap: true. Rules needing over 50,000 candidate evaluations are rejected. Price: $0.05 per call. Also GET /v1/ti…
Calendar converter: Gregorian to Hijri, Hebrew, Japanese era, Persian and more, plus Easter date — Calendar converter: convert a Gregorian date to other calendar systems: Islamic (both the tabular civil calendar and the Umm al-Qura variant), Hebrew, Japanese imperial era, Republic of China, Buddhist and Persian. Also computes Easter Sunday for a year in both the Gregorian and Julian reckonings. Uses the calendar support built into the runtime, with the algorithm named in every response. Price: $0.05 per call. Also GET /v1/time/calendar.
Slug generator: Unicode-aware URL slug with transliteration — Slug generator: turn arbitrary text into a URL-safe slug. Decomposes accents, transliterates German umlauts, Scandinavian and Turkish letters, the ligatures that lose meaning under plain NFD, and Cyrillic (Russian, Ukrainian, Belarusian, Bulgarian, Serbian, Macedonian; language from lang or inferred from the letters). Lowercases, collapses separators, truncates on a word boundary. Returns the slug plus what was removed. Price: $0.05 per call. Also GET /v1/text/slug.
Cyrillic transliteration to Latin (ISO 9:1995, BGN/PCGN Russian) — Cyrillic transliteration to Latin using a named standard: ISO 9:1995 (one-to-one, with diacritics, covering the full standard: Russian, other Slavic, historic and non-Slavic Cyrillic letters) or BGN/PCGN, which is the Russian system only (Ukrainian, Serbian and other letters are passed through unmapped). Returns the transliteration, the source script, the standard, the mapped fraction and the unmapped characters. Other scripts are rejected with UNSUPPORTED_VALUE. Price: $0.05 per call. Also GET…
Unicode normalization (NFC/NFKC), script detection and homoglyph/confusable check — Unicode normalization and confusables check: apply NFC, NFD, NFKC or NFKD, report which forms a string is already in, list the scripts present (all Unicode scripts), and flag confusable and homoglyph characters — Cyrillic а in a Latin word, fullwidth or mathematical look-alikes, all-look-alike words — plus zero-width joiners, bidirectional overrides, invisible and blank characters. Returns per-character detail with code points, names and the ASCII character each imitates. Price: $0.05 per call.…
String similarity: Levenshtein, Jaro-Winkler distance and Soundex/Metaphone phonetic keys — String similarity: compare two strings and return every standard measure in one call: Levenshtein and Damerau-Levenshtein edit distance, normalised similarity, Jaro and Jaro-Winkler, longest common subsequence, Dice coefficient on character bigrams, and the Soundex, Metaphone and NYSIIS phonetic keys of each string. Optional case folding, accent folding and whitespace normalisation before comparison. Price: $0.05 per call. Also GET /v1/text/similarity.
URL parser: parse, canonicalize and extract the registrable domain (eTLD+1) — URL parser: parse and canonicalise a URL, and extract its registrable domain using the Public Suffix List — the part an agent needs to decide whether two URLs belong to the same owner. Returns scheme, host, port, path, decoded query parameters and fragment, the public suffix, the registrable domain (eTLD+1), the subdomain, whether the suffix is ICANN or private, plus a canonical form with default port, dot-segments and percent-encoding normalised. unicode_host uses WHATWG/UTS 46 (non-strict). P…
Punycode converter: IDN domain to ASCII and back, with IDNA2008 label validation — Punycode converter: convert internationalised domain names between Unicode and ASCII punycode in either direction, label by label, and validate each label against IDNA2008: length, leading and trailing hyphens, the hyphen-hyphen rule at positions 3 and 4, disallowed code points and bidirectional rules. Returns both forms, the per-label breakdown and the first rule violated. Strict mode is IDNA2008 (UTS 46 non-transitional); it may reject names /v1/code/url displays. Price: $0.05 per call. Also …
Semver parser: parse and compare versions, check range satisfaction — Semver parser and comparator: parse a semantic version into major, minor, patch, prerelease and build parts; compare two versions by precedence including prerelease ordering; or test whether a version satisfies a range expression using caret, tilde, hyphen, x-ranges and comparator sets. Returns the parsed structure, the comparison result and the reason a range did not match. Price: $0.05 per call. Also GET /v1/code/semver.
Hash generator: SHA-256, SHA-512, SHA-3, Keccak-256, BLAKE2 and HMAC digests — Hash generator: compute a cryptographic digest of supplied data: SHA-256, SHA-384, SHA-512, SHA-1, SHA3-256, SHA3-512, Keccak-256, BLAKE2b-256 and BLAKE2b-512, plus HMAC with any of them. Input is UTF-8 text, base64 or hex bytes; output is hex, base64, base64url or base32. Returns the digest, the byte length of the input, and the exact algorithm identifier used. Price: $0.05 per call. Also GET /v1/code/hash.
JWT decoder: header, claims and expiry state (no signature verification) — JWT decoder: decode a JSON Web Token without verifying it: returns the header, the claims, the signature length and algorithm, and a computed view of the time claims — whether exp has passed, whether nbf is in the future, and the remaining lifetime in seconds against a supplied or current instant. Reports structural problems such as a missing part, invalid base64url or an alg of none. It does not and cannot verify the signature; do not use it to decide trust. Price: $0.05 per call. Also GET /v1…
Geohash encoder and decoder with neighbour cells — Geohash encoder and decoder: encode a WGS-84 latitude and longitude to a geohash at a chosen precision, or decode a geohash back to its bounding box, centre point and error bounds in metres. Encoding also returns the eight neighbouring cells, which is what a caller needs to do proximity search over a geohash-indexed store without a spatial database. Price: $0.05 per call. Also GET /v1/geo/geohash.
Plus code (Open Location Code) encoder and decoder — Plus code (Open Location Code) encoder and decoder: encode coordinates as a plus code at a chosen length, or decode a full code back to its bounding box and centre. Also shortens a full code against a reference coordinate and recovers a shortened code given a reference, which is how plus codes are normally exchanged in text. Returns code length, precision in metres and validity. Price: $0.05 per call. Also GET /v1/geo/pluscode.
Point in polygon check, plus bounding box, centroid and area for GeoJSON — Point in polygon check and GeoJSON geometry: point-in-polygon with correct hole handling, bounding box, centroid, signed area in square metres, perimeter length, and ring winding order for a geometry supplied in the request. Accepts Polygon and MultiPolygon, and a GeoJSON Feature wrapping either. Area and length are geodesic on the WGS-84 ellipsoid, correct at any latitude; containment is planar in lon/lat. Price: $0.05 per call. Also GET /v1/geo/polygon.
Distance calculator: geodesic distance, bearing and destination point on WGS-84 — Distance calculator: distance and direction between WGS-84 coordinates: geodesic distance by Vincenty with a haversine fallback, initial and final bearing, the midpoint, and the destination point reached from a start point on a given bearing and distance. Also computes the cumulative length of a supplied coordinate path. Results in metres, kilometres, nautical miles and miles. Price: $0.05 per call. Also GET /v1/geo/distance.
Crypto address validator: detect the blockchain and verify the checksum (EVM, Bitcoin, Solana and more) — Crypto address validator: identify which blockchain an address belongs to and validate its encoding: EVM EIP-55 checksum, Bitcoin base58check and bech32/bech32m with witness version, Solana base58 and on-curve check, Cosmos bech32 with its HRP, Tron, XRP, Litecoin, Dogecoin, Cardano, Polkadot SS58 and Algorand. Returns every chain the address is valid for (ambiguous when several match), the checksummed form for EVM addresses, and the reason a check failed, including unrecognised_format. Price: …
Solidity function selector: Keccak-256, 4-byte selector and event topic from a signature — Solidity function selector and event topic: compute the Keccak-256 hash of a function or event signature and derive the 4-byte selector and the 32-byte topic. Normalises the signature first — strips parameter names, expands uint to uint256 and the other aliases, flattens tuples — so a signature copied from source code produces the same selector as the canonical form. Also hashes arbitrary text or hex bytes with Keccak-256. Price: $0.05 per call. Also GET /v1/chain/selector.
NUTS region lookup: EU statistical region codes, names and hierarchy — NUTS region lookup (EU statistical regions): resolve a NUTS code to its name, country and level, walk up to its parents or down to its children, or search regions by name. Covers all four levels (country, major region, basic region, small region) for the 27 member states and 12 further reporting countries, from the NUTS 2024 classification. Returns the Latin-script and local-language names plus the urbanisation, coastal and mountain typologies. Price: $0.05 per call. Also GET /v1/ref/nuts.
Airport lookup by IATA or ICAO code: name, coordinates, elevation, time zone; nearest airports — Airport lookup by IATA or ICAO code: get the airport's name, city, country, ISO 3166-2 region code, WGS-84 coordinates, elevation and IANA time zone, or find the nearest airports to a coordinate within a radius. Covers every airport worldwide that holds a three-letter IATA code and scheduled service. Returns the code type that matched and the distance in kilometres for proximity results. Price: $0.05 per call. Also GET /v1/ref/airport.
Currency lookup: ISO 4217 codes, names, minor units and cash rounding — Currency lookup by ISO 4217 alphabetic or numeric code: the official English name, minor-unit exponent, fund flag, the smallest cash denomination where it differs from the minor unit, the territories that use it, and historic codes on request. Returns the correct rounding increment for cash amounts, which is what a caller needs to render or settle a price. This route returns currency facts only and never an exchange rate. Price: $0.05 per call. Also GET /v1/ref/currency.
Country lookup: ISO 3166 codes, currency, TLD, UN region and ISO 3166-2 subdivisions — Country lookup: find a country or territory by ISO 3166-1 alpha-2, alpha-3 or numeric code, or by name, and get the other codes, the official and common English names, the UN M49 region and sub-region, the currencies in use, the country-code TLD, and optionally the full ISO 3166-2 subdivision list with each subdivision's type. Also resolves an ISO 3166-2 subdivision code such as NL-NH directly. Names are matched case- and accent-insensitively. Price: $0.05 per call. Also GET /v1/ref/country.
Base converter: integers between number bases 2 to 36 (hex, binary, octal) — Base converter: convert an integer between any two numeric bases from 2 to 36 (hex, binary, octal and more), with arbitrary precision so values far beyond 2^53 are exact. Accepts an optional sign and common prefixes (0x, 0b, 0o), validates every digit against the source base, and returns the value in the target base, in decimal, and as its bit length and digit count. Price: $0.05 per call. Also GET /v1/num/radix.
Number to words in 12 languages, with ordinal and currency forms — Number to words: spell a number out in English, Dutch, German, French, Spanish, Italian, Portuguese, Polish, Russian, Turkish, Swedish or Japanese, in cardinal, ordinal or currency form. Currency form agrees the number with the currency noun and gives real minor-unit names for 19 currencies (EUR, USD, GBP, CHF, SEK, NOK, DKK, PLN, RUB, TRY, CNY, INR, BRL, MXN, CAD, AUD, NZD, CZK, HUF); any other ISO 4217 code uses a fraction such as 56/100. Values up to 10^15. Price: $0.05 per call. Also GET /v…
Statistics calculator: mean, median, standard deviation, quartiles and percentiles — Statistics calculator for a numeric array in one call: count, sum, mean, median, mode, variance and standard deviation honouring ddof (default 1, the sample form; 0 gives the population form) plus always-population *_population fields, min, max, range, the quartiles and interquartile range, skewness, kurtosis, and any requested percentiles. Percentiles use a named interpolation method so the result is reproducible rather than implementation-defined. Price: $0.05 per call. Also GET /v1/num/stats.
Money split: allocate an amount into shares with no rounding loss — Money split: split a money amount into shares without losing or inventing a cent. Divide evenly into N parts, or by a list of ratios, and the remainder is distributed one minor unit at a time by a named, deterministic rule — largest-remainder, first-wins or last-wins — so the parts always sum exactly to the original. Uses the ISO 4217 minor-unit exponent of the currency, so zero- and three-decimal currencies work (JPY 0, KWD 3); metals and XXX are rejected. Price: $0.05 per call. Also GET /v1/n…