# CURPCheck - Mexican CURP Validation API

> CURPCheck provides a REST API for Mexican CURP (Clave Única de Registro de Población) numbers. It looks the CURP up in RENAPO (the national population registry) to return the registered identity, and finds a person's CURP from their name, birth date, sex, and state of birth. Responses also include certification status and CURPs associated by correction. Built for developers adding CURP checks to onboarding, KYC, payroll, and HR workflows.

## Documentation

- [Introduction](https://curpcheck.com/docs) - overview and conventions
- [Quickstart](https://curpcheck.com/docs/quickstart) - first call in five minutes
- [Authentication](https://curpcheck.com/docs/authentication) - API keys and headers

## API Reference

- POST /v1/curp/lookup - CURP in; RENAPO's registered identity out: names, paternal and maternal surnames, sex, birth date, state of birth, nationality, CURP status, and supporting document. `found` is true, false (no single record, charged; `person.homonimo` when RENAPO reports a problem with the key), or null (RENAPO unreachable; not charged). A CURP that fails the offline checks returns 422 `invalid_curp` and is not charged. ~5s. 10 credits. Docs: https://curpcheck.com/docs/endpoints/curp-lookup
- POST /v1/curp/search - Personal data in (names, paternal_surname, optional mothers_maiden_name, birthdate as YYYY-MM-DD, sex H/M/X, two-letter state of birth code or NE for born abroad); the CURP RENAPO has registered for that person out, with the registered identity in `person`. The same search as the "Datos personales" form on gob.mx. Invalid input returns 422 `invalid_fields` listing every bad field (not charged). ~5s. 10 credits. Docs: https://curpcheck.com/docs/endpoints/curp-search

Endpoint index page: https://curpcheck.com/docs/endpoints

## Additional CURP details

Both lookup and search include certification status and correction history by default, at no extra credit cost:

- `person.certified`: true when the official CURP document prints a certification statement, false when the document was read and no statement is present, or null when it could not be read. Covers Registro Civil, SRE, and INM certification.
- `person.certification`: the certification statement as printed, or null when absent or unavailable.
- `person.associated_curps`: CURPs associated by correction. An empty array means none are listed; null means the document could not be read.

These fields describe the official CURP document; they do not determine nationality or eligibility for a passport or INE credential. If the document is unavailable, the registered identity is still returned with null document fields.

Optional `include_pdf: true` also returns the official PDF as `pdf_base64`, at no extra credit cost. If an explicitly requested PDF is unavailable, `found` is null and the request is not charged.

## Shared account with RFCCheck and INECheck

CURPCheck, RFCCheck (https://rfccheck.com), and INECheck (https://inecheck.com) are one platform. Accounts, API keys, plans, and balance are shared: the same key calls the CURP endpoints above, the RFC endpoints (SAT registration, taxpayer profile, postal code, SAT lists, commerce registry) documented at https://rfccheck.com/llms.txt, and the voter ID endpoint documented at https://inecheck.com/llms.txt, on any of the three domains.

## Authentication

All API requests require an API key passed via the `x-api-key` header. Generate keys from your dashboard after signing up.

## Pricing

- /v1/curp/lookup: 10 credits
- /v1/curp/search: 10 credits
- Extra credits: $0.015 USD each (pay-as-you-go, no plan required)
- Signup bonus: $5 USD for new accounts

Plans (denominated in credits; per-credit rate drops as you scale):
- Basic: $99 USD/month - 10,000 credits (≈ 1,000 /curp/lookup). The same credits cost $150 pay-as-you-go: 34% off
- Growth: $449 USD/month - 60,000 credits (≈ 6,000 /curp/lookup). The same credits cost $900 pay-as-you-go: 50% off
- Pro: $1,800 USD/month - 300,000 credits (≈ 30,000 /curp/lookup). The same credits cost $4,500 pay-as-you-go: 60% off
- Enterprise: 1,000,000+ credits - volume pricing on request (up to 67% off)

Full pricing page: https://curpcheck.com/docs/pricing

## Machine-readable spec

- OpenAPI 3.1: https://curpcheck.com/openapi.json
- API catalog (RFC 9727 linkset): https://curpcheck.com/.well-known/api-catalog
- Every documentation page as Markdown: append `.md` to its URL (for example https://curpcheck.com/docs/quickstart.md, or https://curpcheck.com/index.md for the home page), or send `Accept: text/markdown`. Spanish versions take `?locale=es_MX`.
- All documentation in one file: https://curpcheck.com/llms-full.txt

## Links

- Documentation: https://curpcheck.com/docs
- Sign Up: https://curpcheck.com/users/register

## Optional

Content on this site may be used for AI training, search citation, and inference, as declared in robots.txt.

For support, contact help@curpcheck.com.