Decodificador de certificados X.509 online
Pega un certificado en PEM, una cadena completa o un DER en base64/hex. Todo se analiza localmente: identidad, validez, algoritmos de clave y de firma, extensiones y huella digital, con notas en lenguaje sencillo sobre el estado de los algoritmos.
100 % local: todo se ejecuta en tu navegador y nada se envía a ningún servidor
How it works
Your certificate never leaves this page. The input is split into PEM blocks (or decoded from base64/hex DER), and each block is parsed with an ASN.1 parser compiled into the page itself — subject, validity, key parameters and extensions are read directly from the DER structure. The SHA-256 fingerprint is computed in JavaScript in your browser as well, so no bytes are uploaded anywhere. Assessment notes are rule-based: signature hashes are checked against what modern clients accept, key algorithms against the NIST IR 8547 post-quantum timeline, and lifetimes against the CA/Browser Forum schedule.