Check the check digit of a Mexican CURP or the format of an RFC number and read off the birthdate it encodes - locally in your browser, with no upload.
Running locally on your device ...
Running locally on your device ...
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Your files never left your device
No. Everything runs in your browser - your file never leaves your device. How this is verifiable
The CURP (Clave Unica de Registro de Poblacion, 18 characters) identifies people in Mexico and encodes birthdate, sex and state of birth directly in its structure. A final check character is computed from a fixed value table and a weighted digit sum - this tool recomputes it and, at the same time, reads off the birthdate, sex and state of birth from the structure.
The RFC (Registro Federal de Contribuyentes, 12-13 characters) identifies taxpayers: 4 letters plus a birthdate for natural persons, 3 letters plus an incorporation date for companies, each followed by a 3-character homoclave. That homoclave is assigned by the Mexican tax authority SAT via internal, non-publicly-documented software - this tool therefore honestly checks only format and date, without recomputing the homoclave itself or faking a check it cannot perform.
The whole calculation runs entirely locally in your browser in pure JavaScript - the CURP or RFC is not uploaded, not stored, and no foreign library is loaded from a CDN. You can download the result as a JSON file or read it directly.
| Input formats | Text input |
|---|---|
| Output format | JSON |
| Batch processing | No |
| Processing | Locally in your browser (JavaScript) |
| File upload | None |
Limitations: This tool performs only a mathematical checksum/format check. It is not an official identity, existence, or registry verification and not a request to any authority. Any additional information derived from the number's structure is based solely on the publicly documented encoding logic of the issuing authority. In addition: for the RFC, only format and date are checked - the 3-character homoclave is assigned by SAT via non-publicly-documented internal software and is therefore not recomputed.
No. The check runs entirely locally in your browser; the number never leaves your device and is not stored.
No, honestly not: SAT assigns the homoclave via internal, non-publicly-documented software. This tool only checks format and date, never the homoclave itself.
Because the RFC only carries the year as two digits - the century is not unambiguously derivable from that alone. The tool honestly shows both readings instead of guessing one.
Birthdate (including the century, which a dedicated marker in the code fixes unambiguously), sex (H for male, M for female) and the 2-letter state code - no registry lookup, only the publicly documented encoding logic.
By length: 18 characters are checked as a CURP, 12 or 13 characters as an RFC.