European API · credit packs, no subscription
Catch a bad value before it reaches your database
An email whose domain accepts no mail, an IBAN with a wrong check digit, a made-up VAT number: they all pass your forms and cost you later. Nineteen free checks here, the same engine over API for your code.
No credit card · JSON response · hosted in Europe
Try it right now
Nineteen checks, all free
Every tool computes the format's official check digit — Luhn, mod-97, mod-11 — inside your browser. Nothing is transmitted, nothing is billed.
Business
The same engine, as an API
One call, one JSON verdict. No SDK to install, no subscription: you buy credits, one verification spends one.
What the API adds to the free tools
The domain's MX record
A browser cannot query DNS for you. The API does: if the domain has no mail server, the address will bounce whatever its syntax.
A disposable-domain list that stays current
The one running in your browser fits in a file; the server-side one tracks the thousands of domains temporary-inbox services open every month.
The numbering plan of 240 countries
Knowing a number is a Belgian mobile and not a Swiss landline takes a complete prefix database, and it keeps changing.
Bulk processing, from your own code
Cleaning 40,000 rows is not done by pasting text into a field. One HTTP call per row, one JSON verdict per row.
curl -X POST https://data-checker.fr/api/v1/validate \
-H "Authorization: Bearer dck_live_…" \
-H "Content-Type: application/json" \
-d '{"type":"email","value":"contact@example.com"}'{
"type": "email",
"valid": true,
"syntaxValid": true,
"domain": "example.com",
"mxFound": true,
"disposable": false,
"credits_remaining": 99
}Credits, not a subscription
One-off payment. Credits never expire and work across every check type.
Frequently asked questions
Why are the tools on this site free?
Because they cost nothing to run. A check-digit test — Luhn, mod-97, mod-11 — is a few microseconds of arithmetic executed in your browser: no server to pay for, no third-party API to bill. What does cost money is the DNS lookup and the disposable-domain database, and that is precisely what the API sells.
Does my data pass through your servers?
Not for the site's tools: the value you type never leaves your machine, so there is nothing to intercept and nothing to log. Two tools are the exception and say so on their page — the SIRET existence check and the SPF/DMARC audit query a public service, but the request leaves YOUR browser, never ours.
Does a 'valid' value necessarily exist?
No, and that is the limit worth remembering. A check digit proves a number is well formed, not that it designates anything. An IBAN with a correct mod-97 may match no account; a SIRET with a valid Luhn may never have been issued. Every page states what its check proves and what it does not.
What does the API cost?
Credit packs, no subscription: 1,000 verifications for €9, 10,000 for €49, 50,000 for €149. One credit is one verification, whatever the type. Credits never expire and nothing renews on its own.
Do I need an account to use the tools?
No. All nineteen tools work without signing up and without usage limits. An account only exists to get an API key — and it comes with 100 free verifications, no credit card.
A hundred verifications to see for yourself
Create an account, grab a key, call the API. No credit card required.
Free API key — 100 verifications