Do I need an API key?
No. The validation runs entirely in your browser. The signed verdict uses a throwaway demo key that the page requests from the live AffixIO API on its own.
Public tool
Is this tax ID valid?
Pick a country and type a VAT or tax identification number. VAT Number Validator checks the country format and runs the official checksum where one exists, for over one hundred countries, entirely in your browser, then asks the live AffixIO API for a signed yes or no.
- No API key
- No network call, runs in your browser
- Signed with ML-DSA-65
Tax ID to validate
Pick a country and type the number. The country prefix is optional. The check is instant and runs entirely in your browser.
AffixIO proof
- Proof
- Answer
- Audit
- Policy
- Signed
- Algorithm
- Digest
- Signature
Stamped by the live AffixIO API and signed with ML-DSA-65, the FIPS 204 post-quantum algorithm. Nothing personal goes into the payload.
How to use it
Three moves, no sign-up.
Pick a country and type the number
Choose the country from the list, then type the VAT or tax identification number. The country prefix is optional.
Press Validate
The tool checks the country format and runs the official checksum where one exists. It runs entirely in your browser.
Read the verdict
A YES means the format and checksum both pass. A NO tells you which check failed, with a signed proof from the live AffixIO API.
What you are looking at
Every country has its own format for VAT and tax identification numbers: a country code, a fixed length, and often an official checksum. VAT Number Validator holds the format rules for over one hundred countries.
Where a country publishes an official checksum algorithm, the tool runs it. Many EU countries use a MOD-based check. Where no public algorithm exists, the tool falls back to format and length validation.
The proof card shows the answer stamped by the live AffixIO API: a proof id, an audit id, the policy version, and an ML-DSA-65 signature over the payload digest.
Questions
Does this check the number against a government database?
No. It checks the format and runs the official checksum where one exists. It does not contact any government service.
How many countries are covered?
Over one hundred, with format rules and checksums where publicly available.
What does the proof card show?
The answer stamped by the live AffixIO API: a proof id, an audit id, the policy version, and an ML-DSA-65 signature over the payload digest.