Cert Inspector

Paste one local X.509 certificate as PEM, Base64 or hexadecimal DER. Ordinary inputs update directly; inputs longer than 32,768 characters require Inspect certificate (Ctrl/⌘+Enter). SHA-256 and SHA-1 hash the exact DER bytes; SHA-1 is included for comparison with older records.

The time window only compares the encoded dates with your device clock. No signature, chain, hostname or revocation checks are performed. The algorithm and encoded key parameters do not establish security strength. Unknown extensions are shown by name and byte count.

Maximum 1 MiB DER / 2 MiB text. Multiple PEM blocks and trailing data are rejected. Your exact input stays locally in this browser, including unfinished or invalid text. No decoded fields or fingerprints are saved. Nothing is uploaded. Browser storage limits still apply.