You are responsible for key management and output validation.
Certificate Decoder: Inspect X.509 Certificates Locally
Parse PEM certificates in your browser and inspect subject, issuer, validity, public key, extensions, and SHA-256/SHA-1 fingerprints. Certificates never leave your device.
Parsing runs entirely in your browser with no network request. Paste any public certificate — nothing is uploaded.
Frequently Asked Questions
Is the certificate uploaded anywhere?
No. Parsing happens locally in your browser with the Web Crypto API. You can confirm by opening DevTools → Network and watching for requests while pasting.
What formats are supported?
PEM (BEGIN CERTIFICATE blocks) and base64-encoded DER both work. For a certificate chain, paste all blocks and only the first certificate is decoded.
What do the fingerprints mean?
SHA-256 and SHA-1 fingerprints are hashes of the certificate's DER bytes. Compare them with the fingerprint published by the issuer or service to catch mismatches.