Decode an X.509 certificate and read its fields the way openssl x509 -text prints them: version, serial number, subject and issuer, validity dates, public key, SHA-1/SHA-256 fingerprints and the full extension list. The parser is compiled to WebAssembly and runs entirely in your browser, so certificates — including internal ones — are never uploaded. It only describes the certificate: no signature, chain or revocation checks are performed.