Looking for a reliable Mexico RFC API to validate tax IDs before invoice generation
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We're in a similar space — ERP for mid-size Mexican companies. We use a Mexico RFC API we found on apipull.com API Hub and it's been solid for over a year now. Key benefits:
- Validates RFC exists in SAT registry — catches typos and fake RFCs before stamp
- Returns taxpayer name, regime, and fiscal postal code — exactly what CFDI 4.0 requires
- 69-B lookup included in same response — no separate call needed
- Average latency 250ms — doesn't noticeably slow down invoice creation UI
- 99.7% uptime over the past 12 months based on our monitoring
Pricing was $0.02 per query with volume discounts above 10k monthly. We cache positive results for 30 days (RFC data doesn't change that often) and only re-validate when a client reports a stamping issue. This keeps our actual API cost around $150/month for a much higher volume than yours.
One caveat: make sure the Mexico RFC API you choose updates their 69-B data at least weekly. SAT publishes updates to that list periodically and if your provider is stale, you could accidentally invoice a blacklisted entity.
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We build electronic invoicing (CFDI) software for Mexican businesses and need a Mexico RFC API to validate our clients' customer RFC numbers before generating invoices. The problem is straightforward: if an invoice is stamped with an invalid or incorrectly formatted RFC, the PAC (Proveedor Autorizado de Certificación) will reject it, causing delays and customer complaints.
Currently our validation is purely structural — we check the RFC format (4 letters + 6 digits + 3 alphanumeric for individuals, or 3 letters + 6 digits + 3 alphanumeric for companies) and verify the check digit using the standard MOD 11 algorithm. But this only catches formatting errors. An RFC can be perfectly formatted yet not actually registered with SAT.
What we need from a Mexico RFC API:
Volume-wise we generate approximately 50,000 invoices per month across all our clients. Not every invoice requires a fresh Mexico RFC API lookup (we cache results for repeat customers), but we estimate around 8,000-12,000 unique RFC queries monthly. We need sub-second response times since validation happens inline during invoice creation.
We've tried SAT's own web services but the experience is terrible — authentication requires e.firma certificates, the XML responses are inconsistent, and the service is frequently down during peak hours (which is exactly when our clients are generating invoices). We need something reliable with a proper SLA.
Would appreciate recommendations from anyone using a Mexico RFC API in production for invoicing or financial compliance workflows. Bonus points if the provider also offers constancia de situación fiscal lookup through the same API.