# Free Validation APIs

Page: https://free-web-services.com/web-services/web-development/validators/

Validation APIs check data before you store or use it: phone numbers, bank account numbers (IBAN), EU VAT numbers, names, addresses, spelling and HTML. Use them in forms and imports to catch typos and fake entries early.

## Services

| Service | API key | Formats | Free use |
|---|---|---|---|
| [Address Validation Plus](https://free-web-services.com/web-services/web-development/validators/address-geocoding-address-validation-plus.md) | - | - | Free to try. |
| [DNS over HTTPS (Google Public DNS)](https://free-web-services.com/web-services/web-development/validators/dns-over-https-google-public-dns.md) | Not needed | JSON | Free, no key needed. |
| [LanguageTool API](https://free-web-services.com/web-services/web-development/validators/languagetool-api.md) | Not needed | JSON | - |
| [Name API](https://free-web-services.com/web-services/web-development/validators/nameapi.md) | - | XML | Free and paid plans. |
| [Nu HTML Checker (W3C)](https://free-web-services.com/web-services/web-development/validators/nu-html-checker-w3c.md) | - | - | Free and open source; for heavy use, run your own copy of the checker. |
| [numverify](https://free-web-services.com/web-services/web-development/validators/numverify.md) | Needed, free | JSON | The free plan gives 100 requests per month with a free API key, without a time limit; paid plans give more requests. |
| [OpenIBAN](https://free-web-services.com/web-services/web-development/validators/openiban.md) | Not needed | JSON | Free and open source, no key needed. |
| [VIES VAT number validation](https://free-web-services.com/web-services/web-development/validators/vies-vat-number-validation.md) | Not needed | JSON, XML | Free, no key needed. |

## Questions

**Which free validation APIs work without an API key?**  
DNS over HTTPS (Google Public DNS), LanguageTool API, OpenIBAN and VIES VAT number validation work without a key, according to their documentation. Most keyless services ask you to keep the number of requests reasonable, and some ask for a User-Agent that names your app.

**Are these validation APIs really free?**  
The services here can be used without paying, at least on a free plan or free tier, often with limits such as a number of requests per day or non-commercial use only. The table above quotes what each service says about its free use; check the provider's own terms before you rely on it.

**How up to date is this list?**  
The address of every service is checked about once a week, and services that stop working or stop being free are removed. This list last changed on November 1st, 2026.