#validation

EU VAT identification number format validation as an API, computed locally and deterministically. The validate endpoint takes a VAT number, strips spaces, dots and hyphens, reads the two-letter country prefix and checks the remaining body against that member state’s official structure — Germany’s nine digits, Austria’s U-plus-eight, the Netherlands’ nine-digits-B-two, France’s two-character prefix plus nine digits, Italy’s eleven digits, and so on for all 27 EU countries plus Northern Ireland (XI), correctly using EL for Greece rather than GR. It returns whether the format is valid, the country, and the expected pattern, so DE123456789 and ATU12345678 pass while a German number with only eight digits or a US prefix is rejected. The format endpoint looks up the expected VAT pattern for any country code, or lists all supported ones. This is an offline structure check — a valid format does not prove the number is registered, for which a live VIES lookup is needed. Everything is computed locally and deterministically, so it is instant and private. Ideal for e-commerce, invoicing, accounting, B2B-checkout and tax-compliance app developers, VAT-field validation and onboarding tools, and finance software. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 2 endpoints. This validates VAT-number format; for VAT tax rates use a VAT/tax API.

api.oanor.com/vatid-api

SWIFT/BIC business-identifier-code validation and parsing as an API, computed locally and deterministically. The validate endpoint checks that a code follows the ISO 9362 BIC structure — four letters for the institution, a two-letter ISO country code, a two-character location code and an optional three-character branch code, eight or eleven characters in total — ignoring spaces and upper-casing the input, and confirms the country code is a recognised one; DEUTDEFF (Deutsche Bank, Frankfurt) is a valid eight-character head-office BIC and DEUTDEFF500 a valid eleven-character branch BIC. The parse endpoint breaks a BIC into its institution, country, location and branch components, reports whether it is a head office or a branch (branch XXX or none means the head office), and reads the status from the location code’s second character — 0 for a test/non-SWIFT code, 1 for a passive participant and 2 for reverse billing. A BIC carries no checksum, so this is structural validation. Everything is computed locally and deterministically, so it is instant and private. Ideal for fintech, banking, payment, KYC, treasury and accounting app developers, SWIFT-code and bank-identifier tools, and onboarding flows. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 2 endpoints. This validates and parses a BIC; for IBAN account-number validation use an IBAN API.

api.oanor.com/bic-api

ISBN validation and conversion as an API, computed locally and deterministically. The validate endpoint detects whether a code is an ISBN-10 or an ISBN-13, ignores hyphens and spaces, and verifies the check digit — ISBN-10 with the mod-11 scheme whose last character may be the letter X (for 10), and ISBN-13 with the weighted 1-3-1-3 mod-10 scheme — so 0-306-40615-2 and 978-0-306-40615-7 both validate while a wrong check digit is rejected. The checkdigit endpoint computes the trailing check digit for a 9-digit ISBN-10 stem or a 12-digit ISBN-13 stem (and recomputes it for a full code). The convert endpoint converts between the two forms: an ISBN-10 becomes an ISBN-13 by prefixing 978 and recomputing the check, and a 978-prefixed ISBN-13 converts back to ISBN-10 (979-prefixed codes have no ISBN-10 equivalent). Everything is computed locally and deterministically, so it is instant and private. Ideal for publishing, library, bookstore, catalogue, e-commerce and metadata app developers, ISBN-validation and barcode tools, and inventory systems. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is ISBN-specific validation and conversion; for generic Luhn/Verhoeff check digits use a check-digit API.

api.oanor.com/isbn-api

Add and verify check digits with the standard algorithms — Luhn (mod 10), Verhoeff, Damm and ISO 7064 mod 97-10 — on any number. The generate endpoint returns the check digit(s) and the complete number; the validate endpoint tells you whether a number's check digit is correct. Luhn is the familiar mod-10 scheme behind credit cards, IMEI and many ID numbers; Verhoeff and Damm are single-digit schemes that also catch all adjacent-transposition errors; mod 97-10 produces two check digits and is the scheme used by IBAN. Perfect for generating and validating reference, account, membership and order numbers, and for data-entry integrity. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 4 endpoints. Distinct from credit-card and barcode validators, which apply a fixed algorithm to one specific number format.

api.oanor.com/checkdigit-api

Validate and decode Indian GSTINs (the 15-character Goods & Services Tax Identification Number) instantly and entirely offline. The validate endpoint checks the structure and recomputes the official GSTIN check digit — the base-36 weighted algorithm the GSTN itself uses — and confirms the embedded state code is real, returning a clear valid/invalid verdict with the specific reasons a number fails. The decode endpoint breaks a GSTIN into its parts: the GST state/UT code and its name, the embedded 10-character PAN, the PAN holder type (company, individual/proprietor, firm/LLP, HUF, trust, government and more, read from the PAN's 4th letter), the entity registration number, the default 'Z' slot and the check digit. A states endpoint returns the full GST state-code reference for building dropdowns and lookups. Everything is pure computation — no network call, no key, no cache — so it is fast and private, ideal for checkout and onboarding forms, invoicing and e-invoice/e-way-bill pipelines, vendor master data cleansing and bulk validation. A structural GSTIN validator and decoder — distinct from EU VAT-number validation (vat), IBAN bank-account validation (iban) and card-number checks (creditcard). Note: this verifies the number's structure and check digit, not whether it is actively registered in the GSTN portal. No upstream key, no cache.

api.oanor.com/gst-api

Validate JSON against JSON Schema, server-side. Check any data against a schema (Draft-07 or 2020-12) and get a clear pass/fail plus a detailed list of every error with its instance path, failing keyword and message; verify that a schema itself is well-formed; or infer a starter JSON Schema automatically from a sample document, complete with detected formats like email, URI and date. Built on the battle-tested Ajv engine with full format validation. Every endpoint accepts GET (JSON-encoded parameters) or a JSON POST body and runs entirely locally with no third-party upstream, so responses are instant and the service is always available. Ideal for API request/response validation, form and data-entry checks, ETL and data-quality pipelines, no-code platforms and contract testing.

api.oanor.com/jsonschema-api

A fast, fully-local payment-card toolkit: validate card numbers with the Luhn (mod-10) checksum, detect the brand by IIN/prefix (Visa, Mastercard including the 2-series, American Express, Discover, Diners, JCB, UnionPay, Maestro), format and mask numbers with brand-correct grouping, list supported brands with their valid lengths and CVV length, and generate synthetic Luhn-valid TEST card numbers for QA. Pure server-side compute, no third-party upstream, and inputs are never logged. It is algorithmic only (no real issuer/bank BIN-database lookup). Ideal for checkout forms, payment flows, fraud pre-checks and test fixtures.

api.oanor.com/creditcard-api

Validate IBANs with the ISO 7064 mod-97 checksum and per-country length and structure checks, and resolve the BIC and bank details for supported countries. A local parse endpoint works for every IBAN country offline; the validate endpoint adds bank-code verification and BIC. Ideal for payments, billing, onboarding and KYC.

api.oanor.com/iban-api

Validate, parse and format phone numbers using Google libphonenumber: validity check, E.164 / national / international / RFC-3966 formats, country and calling code detection, and line type (mobile, fixed-line, VoIP, toll-free, premium-rate). Covers every country.

api.oanor.com/phone-api

Verify email addresses without sending anything: RFC syntax validation, live MX-record lookup, disposable/throwaway detection (5,500+ domain blocklist), role-account and free-provider flags, "did you mean" typo suggestion, and a 0–100 deliverability score.

api.oanor.com/email-api