Free Brazilian CPF & CNPJ Validator Online
Enter the number to check whether its check digits are valid. For a CNPJ, we also look up the real registration data at Receita Federal.
Validation runs entirely in your browser, using the same modulo-11 algorithm as Brazil's tax authority (Receita Federal) — no CPF is ever sent to any server. Only for CNPJ, once the number checks out, we look up the public registration data (company name, status, activity) directly from Receita Federal.
We auto-detect CPF (11 digits) or CNPJ (14 digits).
This tool only confirms whether the number is mathematically valid (correct check digits) — it doesn't guarantee the document exists, is active, or belongs to whoever entered it. CNPJ data comes from Receita Federal via BrasilAPI and may be outdated.
Validation algorithm (modulo 11) verified on 2026-09, per Receita Federal's specification.
CPF & CNPJ questions
How does CPF and CNPJ validation work?
The last two digits of a CPF or CNPJ are check digits, calculated from the other numbers using a public formula (modulo 11) defined by Receita Federal. If the calculation matches the given digits, the number is valid — but that doesn't confirm it was actually issued.
Does a valid CPF mean it really exists?
Not necessarily. Mathematical validation only confirms the number follows the formula — it doesn't check any Receita Federal database, because there's no public CPF lookup for privacy reasons.
Where does the CNPJ data shown here come from?
From Receita Federal, through BrasilAPI (a free, open aggregator of official Brazilian public data). It's the same public data available on Receita's official registration certificate.
Why did my CPF or CNPJ show up as invalid?
Usually a typo in one of the digits. Double-check the original number on the physical document. Sequences like 111.111.111-11 are always invalid by definition, even though they look like the right format.