SSL Certificate Decoder
Decode and inspect SSL/TLS certificates
What is SSL Certificate Decoder?
SSL Certificate Decoder parses PEM-encoded X.509 certificates and displays all fields in a readable format — subject, issuer, validity dates, SANs, key usage, and fingerprints. Essential for debugging HTTPS issues and verifying certificate details.
How to use
- Paste a PEM-encoded certificate (the text between -----BEGIN CERTIFICATE----- and -----END CERTIFICATE-----).
- View the decoded fields: subject, issuer, serial number, validity period, SANs, and key details.
- Check expiration status and copy individual fields or the full decoded output.
Result
A DevOps engineer receives a new wildcard certificate for *.example.com. They paste the PEM here to verify the SANs include all expected domains, confirm the expiry date is 1 year out, and check the signature algorithm is SHA-256.
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