Paste a certificate
Only the public certificate. Never paste a private key into any website.
Decoded details
Paste a certificate to see the domain names, issuer, expiry date, key and fingerprints.
Decoded in your browser. Nothing is uploaded.
How to get a website's certificate
- In Chrome or Edge, click the icon left of the address bar → Connection is secure → Certificate is valid → Details → Export.
- On a server, run
openssl s_client -connect example.com:443 -showcertsand copy the blocks between BEGIN and END CERTIFICATE. - Paste the text above, or open the exported .crt / .pem file.
What the decoder shows
- Domains (SAN): every hostname the certificate covers. Browsers check this list, not the common name.
- Validity: start and end dates, with a warning when fewer than 30 days remain.
- Issuer: the certificate authority, such as Let's Encrypt, Sectigo or DigiCert.
- Key and signature: RSA 2048-bit or larger, or ECDSA P-256, are today's normal choices. SHA-1 signatures are no longer trusted.
- Fingerprints: unique SHA-256 and SHA-1 hashes, useful for certificate pinning and comparing two files.
Frequently asked questions
Is it safe to paste my certificate here?
Yes. A certificate is public: every visitor's browser receives it. It is decoded in your browser and not uploaded. Never paste the matching private key anywhere.
Can it check a live website by URL?
No. Browsers don't allow web pages to read another site's certificate, so paste or upload the certificate instead.