How to validate a Mexican RFC

How the check digit works

An RFC has 13 characters (individual) or 12 (company): letters, a YYMMDD date, a 2-character homoclave and a check digit. The API checks format and date, and computes the check digit:

1. Take the first 11 or 12 characters; for companies, left-pad with one space to reach 12.
2. Map each character with the SAT table: 0–9 → 0–9, A–N → 10–23, & → 24, O–Z → 25–36, space → 37, Ñ → 38.
3. Multiply by weights 13, 12, …, 2 and add up.
4. r = 11 − (sum mod 11): if r = 11 the digit is 0, if r = 10 it is A, otherwise r.

The generic RFCs XAXX010101000 and XEXX010101000 are accepted.

Validate with the API

Direct use is free: 50 requests per IP per day, no signup. Endpoints: POST /validate, POST /batch, GET /generate/{doc_type} (for testing only: synthetic data, not real identities).

curl

curl -X POST "https://validalatam.ia-latam.app/validate" -H "Content-Type: application/json" \
  -d '{"type":"MX_RFC","value":"UKUS790523S70"}'

# synthetic test data only / solo para pruebas
curl "https://validalatam.ia-latam.app/generate/MX_RFC"

Python

import requests

BASE = "https://validalatam.ia-latam.app"

r = requests.post(f"{BASE}/validate", json={"type": "MX_RFC", "value": "UKUS790523S70"})
print(r.json()["valid"], r.json()["formatted"])

Real API response (synthetic value from /generate)

UKUS790523S70 (MX_RFC):

{"valid":true,"type":"MX_RFC","country":"MX","input":"UKUS790523S70","normalized":"UKUS790523S70","formatted":"UKUS790523S70","error":null,"details":{"entity":"person"}}

Plans

For AI assistants (MCP)

pip install validalatam-mcp

github.com/elmatis172/validalatam-mcp

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