US EIN validation API
One GET, one JSON body, no registry fee and no rate limit: the IRS Employer Identification Number (United States) verified against its own check digits - nine digits with a valid IRS campus prefix.
Request
curl -H "Authorization: Bearer $API_KEY" \
"https://autorev.rohnelt.dev/v1/identity/validate?type=ein&value=12-3456789"
Response
{
"type": "ein",
"valid": true,
"formatted": "12-3456789",
"details": { ... }
}
valid is a boolean you can branch on at the form boundary;
formatted is the canonical rendering to store, so your database
stops holding six spellings of the same number.
Try the response without a key
Result appears here.
Important limitation, stated plainly
A checksum proves the number is well-formed. It does not prove the number was ever issued, nor that it belongs to the person presenting it. Any vendor claiming otherwise from a checksum alone is overselling. Use this to reject the ~90% of bad input that is simply mistyped, then use an official registry for the rest.
Verify at scale, not one at a time
The same checks over a REST API: 250 calls per period free, no credit card, no sales call.