SSL Certificate Decoder
Decodes X.509 certificates from PEM text: subject and issuer, validity period with days remaining, subject alternative names, key algorithm and size, serial number and signature algorithm — parsed entirely in your browser.
Runs 100% in your browser — nothing you paste leaves your device.
Read the full guide to this tool
Notes
- Get the PEM from your server config, from `openssl s_client -connect host:443 -showcerts`, or by exporting it in the browser's certificate viewer.
- Browsers match the hostname against the Subject Alternative Names only — the Common Name has been ignored since 2017.
- Runs 100% in your browser — nothing you paste leaves your device.
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