SSL Certificate Decoder

Decode basic fields from a PEM-formatted X.509 certificate. Free online tool, no upload. View expiry, issuer, and subject.

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Your file will stay on this device.

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Frequently asked questions

Does it fully validate?
No. Best-effort field extraction. Does not verify signatures, chains of trust, or hostname matching.
Why Unknown fields?
Not a full ASN.1 parser. Unusual encodings may not be detected. Use openssl x509 -text for authoritative output.
Is my cert uploaded?
No. All decoding happens in your browser. The PEM never leaves your device.