Certificate Decoder
Auto-detect and decode any X.509 certificate, CSR, or PEM block — universal certificate inspector.
Frequently Asked Questions
Universal Certificate & PEM Decoder
PEM (Privacy Enhanced Mail) is the most common encoding format for cryptographic objects like SSL certificates, CSRs, private keys, and public keys. A PEM file is a Base64-encoded DER (Distinguished Encoding Rules) structure wrapped in -----BEGIN TYPE----- and -----END TYPE----- delimiters.
This universal decoder automatically identifies what type of PEM object you've pasted and routes it to the appropriate parser. X.509 certificates are decoded to show subject, issuer, validity, SANs, and fingerprints. CSRs are decoded to show the requested subject and public key. Private keys are identified but key material is not displayed for security.
All processing is 100% client-side. Certificate data, private keys, and CSR details never leave your browser. This makes the tool safe to use with production certificates in secure environments.