X.509 Certificate Decoder
Decode a PEM SSL/TLS certificate to inspect its details.
The certificate is parsed entirely in your browser and is never uploaded.
100% private - runs entirely in your browser.
Your input, keys and passwords are never uploaded. Want proof? Load this page, then turn off your internet - the tool still works. For an exact check, open your browser's DevTools Network tab and confirm no data is sent when you use it.
About the X.509 Certificate Decoder
Decode an X.509 SSL/TLS certificate in PEM format to inspect who it was issued to, who issued it, and when it expires.
It shows the subject, issuer, validity dates, serial number, signature algorithm, public key, Subject Alternative Names and fingerprints.
The certificate is parsed entirely in your browser and never uploaded.
Key features
- Subject, issuer and validity dates
- Serial number and signature algorithm
- Subject Alternative Names (SANs)
- SHA-256 and SHA-1 fingerprints
How to use
- 1Paste the PEM certificate.
- 2Click decode.
- 3Read the certificate details.
Examples
a PEM certificateSubject, issuer, validity, SANs, fingerprintsSee exactly who a certificate is for and when it expires.
the same certificateValid from and valid to datesQuickly confirm whether a certificate is still valid.
Frequently asked questions
- What certificate format is supported?
- PEM certificates that start with -----BEGIN CERTIFICATE-----. You can copy this from a .pem or .crt file.
- What are Subject Alternative Names?
- SANs are the extra domains and IPs a certificate is valid for, in addition to the Common Name.
- Is my certificate uploaded?
- No. It is parsed entirely in your browser.