
IsValid.dev
Abstract APIs
Numverify
mailboxlayer API
IBAN.com
VAT-calc.net
Melissa Data Quality
MailValidation.io
Code Flex
IsValid is a validation API service for developers who need to quickly verify data formats without building their own validators. It offers 40+ endpoints covering financial identifiers (IBAN, BIC, ISIN, CUSIP), international standards (ISBN, ISSN), technology formats (UUID, JWT, QR codes), regional codes (PESEL, REGON, VAT), and more.
The service works on a freemium model โ 100 free API calls per day, no credit card required. Users manage API keys through a dashboard with usage analytics showing daily call volume and per-endpoint breakdowns.
IsValid.dev
Code FlexIsValid.dev's answer
IsValid offers 70+ validators in a single API โ covering financial identifiers (IBAN, BIC, ISIN, LEI), international standards (ISBN, ISSN), technology formats (UUID, JWT, QR codes), tax numbers (VAT, REGON, PESEL), credit cards, phone numbers, and more. No need to integrate multiple services for different data types.
IsValid.dev's answer
Most validation APIs focus on one category (email or phone). IsValid covers financial, regional, and technical formats all in one place with a consistent REST API. The free tier with 100 calls/day requires no credit card, and integration takes minutes.
IsValid.dev's answer
Developers and software teams building applications that handle user input, financial data, or international identifiers โ particularly in fintech, e-commerce, and SaaS products.
IsValid.dev's answer
IsValid was built out of frustration with piecing together multiple validation libraries and services. The goal was a single, reliable API that handles the full range of data validation needs developers encounter in real-world applications.
IsValid.dev's answer
Next.js, Fastify, PostgreSQL, Docker
Abstract APIs - Simple, powerful APIs for everyday dev tasks
Numverify - Global phone number validation and lookup API
mailboxlayer API - Mailboxlayer is a free, simple and powerful JSON API offering instant email address validation & verification via syntax checks, typo and spelling checks, SMTP checks, free and disposable provider filtering, and much more.
IBAN.com - IBAN checker is a software designed to validate an International Bank Account Number and identify the bank owning this account, BIC code and address.
VAT-calc.net - VAT calculator is an online utility web application that allows users to add or remove value-added tax from any amount.
Melissa Data Quality - Melissa helps companies to harness Big Data, legacy data, and people data (names, addresses, phone numbers, and emails).