SSL Certificate Decoder
Decode PEM-encoded SSL/TLS certificates and view all details — 100% local processing
PEM Certificate
About SSL Cert Decoder
An SSL/TLS certificate binds a public key to a domain and is signed by a certificate authority. Certificates are shared in PEM format, a Base64 block between BEGIN CERTIFICATE and END CERTIFICATE lines, which is unreadable without a tool.
Paste a PEM certificate and this decoder shows its subject, issuer, validity dates, and other fields, in your browser. Certificates are public information, but decoding locally still avoids handing details of your infrastructure to a third-party service.
Common use cases
- Checking when a certificate expires.
- Confirming which domain and organization a certificate was issued to.
- Verifying the issuer while troubleshooting a trust error.
- Inspecting a certificate before installing it.
Frequently asked questions
- Should I paste my private key here?
- No. Only paste certificates, which are public. Never share a private key with any tool.
- Why is a valid-looking certificate rejected by browsers?
- Typical causes are an expired certificate, a name mismatch, or a missing intermediate certificate in the chain.
- What is the difference between subject and issuer?
- The subject is who the certificate identifies; the issuer is the authority that signed it.