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IsValid

Data Validation API

Stop writing validators from scratch. One REST API for emails, IBANs, domains, ISINs, ETH addresses, cron expressions, and 73+ validators — with checksum verification, DNS lookups, ESMA FIRDS data, GLEIF entity search, and UN/LOCODE built in.

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Validators: 73+
Free calls/day: 100
Uptime: 99.9%
SDKs: Node · Python

Featured Validators

A closer look at the most powerful endpoints — enriched with live data from authoritative sources.

Legal Entity Identifiers

LEI Validation & Search

Validate Legal Entity Identifiers (ISO 17442) and instantly enrich them with entity data from the local GLEIF database — no external API calls, no rate limits. Search across 2.3 million entities by name with trigram similarity.

ISO 17442 format validation + mod-97 checksum (same as IBAN)
Local GLEIF Golden Copy database — ~2.3 million entities
Full-text name search with trigram similarity (pg_trgm)
LOU (Local Operating Unit) info returned for every valid LEI

GET /v0/leiView docs →

// GET /v0/lei?value=7LTWFZYICNSX8D621K86

{

"valid": true,

"lei": "7LTWFZYICNSX8D621K86",

"found": true,

"dataSource": "gleif-db",

"entity.legalName": "Deutsche Bank AG",

"entity.country": "DE",

"entity.entityStatus": "ACTIVE",

"entity.registrationStatus": "ISSUED",

"lou.name": "SWIFT"

}

Financial Instruments

ISIN Validation & Lookup

Validate International Securities Identification Numbers (ISO 6166) and instantly enrich them with instrument data. ESMA FIRDS and OpenFIGI are queried simultaneously — both sources merged into a single unified response.

ISO 6166 format validation + Luhn check digit
ESMA FIRDS — EU regulatory database (MiFID II, ~700k instruments)
OpenFIGI — global coverage (US equities and more)
Unified fields: FISN, CFI code, currency, venue, LEI, ticker, FIGI

GET /v0/isinView docs →

// GET /v0/isin?value=PL0000503135

{

"valid": true,

"countryCode": "PL",

"countryName": "Poland",

"found": true,

"dataSource": "firds+openfigi",

"name": "PKN ORLEN SA",

"fisn": "PKN ORLEN SA/SHS",

"cfiCode": "ESVUFR",

"currency": "PLN",

"tradingVenue": "XWAR",

"ticker": "PKN",

"marketSector": "Equity"

}

International Banking

BIC / SWIFT Validation

Validate Bank Identifier Codes (ISO 9362) used in international wire transfers. 8- and 11-character BICs are supported — institution name, city, and branch lookup built in.

ISO 9362 format check — 8-character and 11-character BICs
Bank code, location code, and branch code breakdown
Institution name lookup from a built-in directory
City and branch name returned when available

GET /v0/bicView docs →

// GET /v0/bic?value=XASXAU2SRTG

{

"valid": true,

"bankCode": "XASX",

"countryCode": "AU",

"countryName": "Australia",

"locationCode": "2S",

"branchCode": "RTG",

"bankName": "ASX Operations Pty Limited",

"city": "Sydney",

"branch": "RTGS Settlement"

}

Bank Account Numbers

IBAN Validation

Validate International Bank Account Numbers (ISO 13616) for 80+ countries. Checks country-specific length, structure, and the full MOD-97 checksum — spaces and lowercase letters are handled automatically.

ISO 13616 format validation + MOD-97 checksum algorithm
80+ countries — EU and non-EU alike
Bank identification — name and BIC from 40+ national registries
BBAN extraction, EU membership flag, canonical formatted output

GET /v0/ibanView docs →

// GET /v0/iban?value=PL61109010140000071219812874

{

"valid": true,

"countryCode": "PL",

"countryName": "Poland",

"bban": "109010140000071219812874",

"isEU": true,

"formatted": "PL61 1090 1014 0000 0712 …",

"bankCode": "10901014",

"bankName": "PKO Bank Polski SA",

"bankBic": "BPKOPLPW"

}

Travel & Aviation

IATA Airport Code Validation

Validate 3-letter IATA airport codes and look up rich metadata for 250+ airports worldwide. Instantly retrieve the official name, served city, country, corresponding ICAO code, IANA timezone, and airport classification.

250+ airports across all continents
ICAO code, city, country, and IANA timezone returned
Airport classification: large_airport or medium_airport
Case-insensitive — WAW, waw, and Waw all accepted

GET /v0/iata/airportView docs →

// GET /v0/iata/airport?value=WAW

{

"valid": true,

"found": true,

"iata": "WAW",

"icao": "EPWA",

"name": "Warsaw Chopin Airport",

"city": "Warsaw",

"countryCode": "PL",

"countryName": "Poland",

"timezone": "Europe/Warsaw",

"type": "large_airport"

}

Business & Finance

Banking, payments, securities, and tax identifiers — with checksum verification, enrichment from authoritative databases, and real-time VIES checks.

🏦

IBAN

Validate International Bank Account Numbers for 80+ countries — MOD-97 checksum, bank name and BIC lookup for 40+ countries.

GET /v0/iban

🔀

BIC / SWIFT

Validate Bank Identifier Codes used in international wire transfers. Returns institution name, city, and branch from a built-in directory.

GET /v0/bic

💳

Credit Card

Luhn checksum validation with card network detection — Visa, Mastercard, Amex, Discover, JCB, Diners Club, and UnionPay.

POST /v0/credit-card

📈

ISIN

ISO 6166 validation with Luhn check digit. Enriches with instrument data from ESMA FIRDS and OpenFIGI — name, CFI, currency, venue, ticker.

GET /v0/isin

🏢

LEI

ISO 17442 validation with mod-97 checksum. Looks up entity data from a local GLEIF database of 2.3 million records. Supports name search.

GET /v0/lei

🧾

VAT

EU VAT number validation for all 27 member states with optional real-time VIES verification. Returns country, company name, and validity status.

GET /v0/vat

General Purpose

Everyday validators for contact data, networking, crypto, travel, and developer tokens.

📧

Email

RFC 5322 validation with optional DNS MX record checks to confirm the domain actually accepts mail.

GET /v0/email

📞

Phone Number

Validate phone numbers for 200+ countries. Returns country, calling code, line type, and E.164, national, and international formats.

GET /v0/phone

🌐

Domain

Validate domain names with full DNS resolution. Returns TLD, SLD, IDN detection, and A/AAAA record lookups via Google and Cloudflare DNS.

GET /v0/domain

⟠

ETH Address

Validate Ethereum addresses with EIP-55 mixed-case checksum verification. Returns the canonical checksummed address.

GET /v0/eth-address

✈️

IATA Airport

Validate 3-letter IATA airport codes with rich metadata — official name, city, country, ICAO code, IANA timezone, and classification.

GET /v0/iata/airport

🔑

JWT

Decode and validate JSON Web Tokens — header, payload, signature structure, registered claims, and expiration checks.

GET /v0/jwt

And 60+ more — Bitcoin address, IMEI, EAN / GTIN / UPC, IATA airline, MIC, URL, IP & MAC address, GPS coordinates, postal code, ISBN, ISSN, DOI, ORCID, ABA routing, NPI, CNPJ, CPF, ABN, NIF/NIE, GSTIN, EORI, Sort Code, NUTS, ISO 6346, SSCC, GLN, GS1 prefix, HS code, CAS number, barcode, QR / Data Matrix, NAICS / NACE industry, KRS, PESEL, REGON, DUNS, CEIDG, UUID, semver, CSS color, SWIFT MT, cron, regex, base64, DTI, CUSIP, CFI, and others. See full documentation →

TAC, SNR, and check digit explained — and why a 15-digit regex is not enough.

Read guide →

These are just a few of our guides — covering algorithms, edge cases, and production patterns. See all guides →

Official SDKs

Type-safe clients for Node.js and Python — with automatic retry, custom error classes, and full IntelliSense for every endpoint.

// Quick start

import { createClient } from '@isvalid-dev/sdk';

const iv = createClient({ apiKey: 'your-api-key' });

// Validate an email

const email = await iv.email('user@example.com');

// Country-specific validators

await iv.pl.pesel('44051401358');

await iv.iata.airport('WAW');

Node.js / TypeScript

npm install @isvalid-dev/sdk

Zero dependencies — native fetch only
Full TypeScript types for every response
ESM + CJS dual export — ~1.5 KB min+brotli
Automatic retry with exponential backoff

Get Started GitHub npm

# Quick start

from isvalid_sdk import IsValidConfig, create_client

iv = create_client(IsValidConfig(api_key='your-api-key'))

# Validate an email

email = iv.email('user@example.com')

# Country-specific validators

iv.pl.pesel('44051401358')

iv.iata.airport('WAW')

Python

pip install isvalid-sdk

Single dependency — httpx
Full type hints with TypedDict for every response
Context manager support
Automatic retry with exponential backoff

Get Started GitHub PyPI

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Getting Started Read the Docs