Certificate Parser

Decodes X.509 certificates from PEM format (-----BEGIN CERTIFICATE-----) into structured fields by parsing the raw DER/ASN.1 bytes locally. It extracts version, serial number, issuer and subject distinguished names, validity window, public key details (algorithm, modulus, exponent, curve, key size), signature algorithm, X.509 extensions, and computes SHA-256/SHA-1 fingerprints via the Web Crypto API. A Valid/Expired badge compares validTo to the current time, and the parsed data can be exported as JSON.

1. Either click Upload File to load a .pem/.crt/.cer file, or paste PEM content directly into the textarea. 2. Click Parse; results appear in a structured card and the badge shows Valid or Expired. 3. Use the copy icons next to the serial number and fingerprints to copy those values. 4. Click Export to download all parsed fields as certificate-info.json.

Distinguished name attributes (CN, O, OU, C, ST, L, emailAddress, etc.) and algorithms are resolved through an embedded OID map: RSA (1.2.840.113549.1.1.1), SHA1/256/384/512withRSA, RSASSA-PSS, EC public keys with curves P-256/P-384/P-521, X25519, Ed25519, and ECDSA-with-SHA variants. Common extensions (subjectKeyIdentifier, keyUsage, subjectAltName, basicConstraints, extKeyUsage, authorityInfoAccess, CT precertificate SCTs, etc.) are identified by name. RSA keys expose modulus (hex with colons), exponent, and bit size; EC/EdDSA keys report algorithm and curve.