Validate a payment-card number: Luhn check-digit test plus network detection and length check. A syntactically valid number that fails Luhn returns `valid:false` (a 200, not an error).

Validate a GTIN barcode number — EAN-8, UPC-A (12), EAN-13 or GTIN-14 — by the standard mod-10 check digit. Length selects the scheme.

Compute the standard English readability formulas — Flesch Reading Ease, Flesch–Kincaid grade, Gunning fog, SMOG, Coleman–Liau and ARI — along with the underlying sentence/word/syllable statistics. Empty text is a clean 400.

Hamming distance — the number of positions at which two EQUAL-LENGTH strings differ — plus a normalized similarity. Strings of unequal length are a clean 400.

Damerau-Levenshtein distance — like Levenshtein but also counts adjacent transpositions as a single edit — plus a normalized similarity in [0,1].

TraceFast knowledge graph: every attribute interval an address has held, oldest first — when it became a contract, when its code was removed, when it first held state. Path address: The address, `0x`-prefixed, 40 hex characters, any case. Query limit: 1..=500, default 100. Docs: https://docs.tracefast.xyz/api/address-attribute-history.md

TraceFast live Ethereum data: for each day in a window, how many blocks changed the address's own account state and which kind of change it was (balance, nonce, code, creation). Path address: The address, `0x`-prefixed, 40 hex characters, any case. Query period: `30d`, `90d` (default) or `365d`. Docs: https://docs.tracefast.xyz/api/address-daily-activity.md

Validate a blockchain address. Supply `chain` to check against a specific chain, or omit it to auto-detect. Ethereum addresses report their EIP-55 checksum state; Bitcoin covers base58check (P2PKH/P2SH) and bech32/bech32m segwit (P2WPKH/P2WSH/P2TR). A well-formed but invalid address returns `valid:false` — not an error.

Resolve a Unicode block name (loose matching) to its range, size, count of assigned characters and a small sample. An unknown block is a successful `found:false`. This is a Unicode Character Database block — not a blockchain block.

Validate a Polish VAT (NIP) number against the official VAT register. Validity means the taxpayer's VAT status is active (Czynny).

Compute network details of a CIDR block — network & broadcast address, usable host range, total and usable address counts. Works for IPv4 and IPv6 (counts returned as strings for large IPv6 blocks). Honours RFC 3021 for /31.

Validate a 15-digit mobile device IMEI by its Luhn check digit. Spaces and hyphens are ignored.

TraceFast live Ethereum data: the address's native balance at the end of each day it changed, oldest first, with the net change and the number of balance-changing events per day, the USD value at each closed day's last hour, and totals over the window. Path address: The address, `0x`-prefixed, 40 hex characters, any case. Query limit: Most recent days with a balance change to return, 1..=365, default 90. Docs: https://docs.tracefast.xyz/api/address-balance-history.md

TraceFast live Ethereum data: three different questions about when an address was active, each answered separately — when it was first mentioned anywhere on chain; when its own account state last changed and how many times it changed; and the newest block at which it took part in anything (a top-level transaction, a token transfer, an emitted log, a value-bearing call), with the sources that answer was… Path: address. Docs: https://docs.tracefast.xyz/api/address-activity.md

TraceFast knowledge graph: the attributes an address held at the end of one block, 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-attributes-at-block.md

Requires an unauthenticated caller-owned baseline; returns real current NS/MX records, added/removed sets and tri-state target-provider transition. Current DNS comes from one bounded native recursive-resolver query; existing Dossier provides context. Resolver caching may apply; no account ownership or global migration-completion claim. Existing provider patterns are reused without new invented attribution. At most50records,domain253chars,9sbudget; DNSsubquery2s/oneattempt. Unknown provider remai

Requires an unauthenticated caller-owned baseline; returns real current NS/MX records, added/removed sets and tri-state target-provider transition. Current DNS comes from one bounded native recursive-resolver query; existing Dossier provides context. Resolver caching may apply; no account ownership or global migration-completion claim. Existing provider patterns are reused without new invented attribution. At most50records,domain253chars,9sbudget; DNSsubquery2s/oneattempt. Unknown provider remai

Requires an unauthenticated caller-owned baseline; returns real current NS/MX records, added/removed sets and tri-state target-provider transition. Current DNS comes from one bounded native recursive-resolver query; existing Dossier provides context. Resolver caching may apply; no account ownership or global migration-completion claim. Existing provider patterns are reused without new invented attribution. At most50records,domain253chars,9sbudget; DNSsubquery2s/oneattempt. Unknown provider remai

Validate and decompose IBANs (checksum, country format, IBAN registry, SEPA membership; bank/branch/account parts) and BIC/SWIFT codes. Batches up to 100. Format validation only — does not prove an account exists.

Requires an unauthenticated caller-owned baseline; returns real current NS/MX records, added/removed sets and tri-state target-provider transition. Current DNS comes from one bounded native recursive-resolver query; existing Dossier provides context. Resolver caching may apply; no account ownership or global migration-completion claim. Existing provider patterns are reused without new invented attribution. At most50records,domain253chars,9sbudget; DNSsubquery2s/oneattempt. Unknown provider remai