Digital Certificate
Read a .pfx/.p12 certificate's data — validity, CPF/CNPJ, issuer — without leaving your browser.
The .pfx/.p12 file and the typed password are read and decoded entirely in your browser — not a single byte of either is sent to any server, not even Nexinon's own. Reading the certificate's fields requires unlocking the container with the password first; that happens only in the browser's own memory, and the resulting private key is never displayed, exported, or used for anything else.
What a .pfx/.p12 certificate is
PKCS#12 (.p12 extension) and PFX (.pfx extension) are the same file format under two different names — a password-protected binary container that bundles an X.509 digital certificate with its matching private key in a single file. It's the universal format for carrying and installing a certificate together with its key (browser, operating system, e-CAC, PDF signer), unlike a .cer/.crt file, which carries only the public certificate, without the private key.
e-CPF, e-CNPJ, and ICP-Brasil
ICP-Brasil (Brazil's official Public Key Infrastructure) is the country's official digital certification system, regulated by ITI. An e-CPF is the digital certificate of an individual within that system, tied to their CPF (Brazil's individual taxpayer ID); an e-CNPJ belongs to a company, tied to its CNPJ (Brazil's company registry ID). Both are used to sign documents with legal validity, access the Federal Revenue's e-CAC portal, issue electronic invoices, and authenticate into government systems. ICP-Brasil certificates embed the holder's CPF or CNPJ inside specific technical fields of the certificate itself (checked against ITI's official documentation before this tool was built) — that's what lets this tool extract and display it.
A1 or A3 certificate?
A1 is a file-based certificate (exactly the .pfx/.p12 this tool reads), valid for about a year, installable on any computer. A3 lives on a USB token or smart card — its private key never leaves the hardware, not even to produce a .pfx/.p12 file. That's why any certificate loaded into this tool is necessarily A1: if it exists as an exportable file, it can't be A3 by definition.
.pfx or .p12: what's the difference?
Nothing, technically — they're the same format (defined by the PKCS#12 standard), with different file extensions for historical reasons (.pfx comes from Microsoft's predecessor format, Personal Information Exchange). This tool reads both without distinction.
Frequently asked questions
No, never — not in the browser's localStorage, not anywhere. As soon as you leave the page or verify another certificate, everything is discarded from memory. Not a single byte of the file or the password ever comes near a server.
No — this tool only inspects the certificate's public data (validity, holder, issuer). It never uses the private key to sign anything, even though unlocking it internally is required to read the other fields.
Checking revocation (CRL/OCSP) requires querying an external server over the internet — which contradicts this tool's 100%-local guarantee specifically for that check. It's a deliberate scope boundary, not a hidden limitation.
Because the .pfx/.p12 format encrypts the entire container (certificate and private key together) with the same password — there's no way to read just the certificate without unlocking the file first. Unlocking it materializes the private key in the browser's memory, but it's never displayed, exported, or used for anything.
It means the certificate carries the specific technical fields ICP-Brasil uses to embed the holder's CPF or CNPJ — a reliable sign that it's a genuine e-CPF or e-CNPJ, not just an ordinary certificate issued in Brazil.
Nexinon Principles
Privacy
Your data never leaves your browser.No account needed
Use it now, no account or password.Free
No usage limits, no paid plan.Trustworthy content
Full explanation behind every tool, not just the result.