Best Data Validation APIs in 2026

The top 15 of 16 free Data Validation APIs, ranked by how easy they are to start with (API key, HTTPS, CORS), how reliable they are in our daily health checks, and what developers rate them. US Autocomplete API takes the top spot.

Last tested Oct 24, 2026 · Rankings update daily

1
US Autocomplete API
Online · 976 ms
Enter address data quickly with real-time address suggestions.
- Callable from the browser (CORS)
- HTTPS
apiKeyHTTPSCORS
2
US Street Address API
Online · 559 ms
Validate and append data for any US postal address.
- Callable from the browser (CORS)
- HTTPS
apiKeyHTTPSCORS
3A
Attestwire API
Online · 700 ms
Validate EN 16931 e-invoices: XRechnung, ZUGFeRD, Factur-X, Peppol BIS.
- Callable from the browser (CORS)
- HTTPS
apiKeyHTTPSCORS
4
Postman Echo API
Online · 2932 ms
Test api server to receive and return value from HTTP method.
- No API key needed
- HTTPS
No authHTTPSCORS ?
5T
Temsor API
Online · 668 ms
Validates Turkish national ID, tax number, IBAN, phone, plate and parses addresses.
- Callable from the browser (CORS)
- HTTPS
apiKeyHTTPSCORS
6
US Extract API
Online · 520 ms
Extract postal addresses from any text including emails.
- Callable from the browser (CORS)
- HTTPS
apiKeyHTTPSCORS
7
invowerk API
Online · 727 ms
Validate e-invoices (ZUGFeRD, Factur-X, XRechnung, Peppol BIS) and get a validation report.
- HTTPS
apiKeyHTTPSCORS ?
8
VATlayer API
Online · 887 ms
Free and HTTPS secured JSON API offering instant VAT number validation, reliable EU VAT rates and VAT compliant price calculations for developers & businesses.
- HTTPS
apiKeyHTTPSCORS ?
9
RevAddress API
Online · 966 ms
US address standardization, congressional and state legislative districts, Census data; free tier.
- HTTPS
apiKeyHTTPSNo CORS
10
SchemaShield API
Online · 499 ms
Read-only preflight for breaking schema changes and downstream query impact.
- HTTPS
apiKeyHTTPSCORS ?
11
VerifNow API
Online · 487 ms
Validates email, phone, IBAN, EU VAT against VIES, and Canadian, Spanish and US national IDs.
- HTTPS
apiKeyHTTPSNo CORS
12
Lob.com API
Online · 2690 ms
Automate and personalize direct mail at scale while our nationwide print network speeds delivery, controls postage costs, and keeps every send compliant.
- HTTPS
apiKeyHTTPSCORS ?
13
PurgoMalum API
Online · 702 ms
Content validator against profanity & obscenity.
- No API key needed
No authNo HTTPSCORS ?
14
sthan.io Address Autocomplete API
Online · 1266 ms
Real-time US address suggestions as users type.
- HTTPS
apiKeyHTTPSNo CORS
15
sthan.io Address Parser API
Online · 1387 ms
Parse freeform US addresses into structured fields (house number, street, unit, city, state, ZIP).
- HTTPS
apiKeyHTTPSNo CORS

Data Validation APIs compared

Top Data Validation APIs compared
API	API key	HTTPS	CORS	Uptime	Response	Rating
US Autocomplete	Required	Yes	Yes	Up	976 ms	Not rated
US Street Address	Required	Yes	Yes	Up	559 ms	Not rated
Attestwire	Required	Yes	Yes	Up	700 ms	Not rated
Postman Echo	No	Yes	Unknown	Up	2932 ms	Not rated
Temsor	Required	Yes	Yes	Up	668 ms	Not rated
US Extract	Required	Yes	Yes	Up	520 ms	Not rated
invowerk	Required	Yes	Unknown	Up	727 ms	Not rated
VATlayer	Required	Yes	Unknown	Up	887 ms	Not rated
RevAddress	Required	Yes	No	Up	966 ms	Not rated
SchemaShield	Required	Yes	Unknown	Up	499 ms	Not rated

More Data Validation APIs

Best Data Validation API FAQ

What is the best free Data Validation API in 2026?

Based on access, reliability and developer ratings, the top free Data Validation APIs right now are US Autocomplete API, US Street Address API and Attestwire API. US Autocomplete API ranks first. Rankings update daily from health checks of all 16 Data Validation APIs in the directory.

What is the best Data Validation API without an API key?

Postman Echo API and PurgoMalum API need no API key, so you can call them without signing up. 2 of the 16 ranked Data Validation APIs are keyless.

Which Data Validation API works from the browser?

US Autocomplete API, US Street Address API and Attestwire API support CORS over HTTPS, so front-end JavaScript can call them directly without a proxy.

How are these APIs ranked?

Each API gets a score from: no API key (+), HTTPS (+), CORS support (+), 30-day uptime and response time from our daily health checks, and ratings from developers on this site. APIs that failed three checks in a row are left out until they recover.