🔐 Certificate Decoder
Decode and view X.509 SSL/TLS certificates. Paste your certificate in PEM format to view details including validity, issuer, subject, and extensions.
📝 How to Get a Certificate (Click for Instructions)
Click here for step-by-step instructions
Learn how to export a certificate from your browser...
📖 About X.509 Certificates
- X.509: Standard format for public key certificates used in SSL/TLS
- PEM Format: Base64-encoded certificate between BEGIN/END markers
- Subject: The entity (person, server, organization) the certificate represents
- Issuer: The Certificate Authority (CA) that signed the certificate
- Validity Period: Time range during which the certificate is valid
- Public Key: Used to encrypt data or verify signatures
- Fingerprint: Hash of the certificate for verification
- Common Uses: HTTPS websites, email encryption, code signing
📋 How to Use the Certificate Decoder
- Paste the certificate in PEM format, including the BEGIN and END CERTIFICATE lines.
- Select Decode Certificate.
- Read the subject, issuer, validity dates and extensions such as the Subject Alternative Names.
- Use Clear to decode another.
🎯 When to Use It
- Checking which domains a certificate covers before installing it.
- Confirming the expiry date of a certificate file.
- Inspecting the issuer chain when troubleshooting a trust error.
💡 Tips & Common Pitfalls
- Only paste the public certificate. A private key block starts with BEGIN PRIVATE KEY and should never be shared.
- If decoding fails, make sure the text has no missing line breaks or extra characters around the BEGIN and END lines.
- To get the certificate from a live site, use the Get Cert from a Domain button for instructions.
- Compare the Subject Alternative Names with the domain you serve. A mismatch causes browser warnings.
❓ Frequently Asked Questions
What is a PEM certificate?
PEM (Privacy Enhanced Mail) is a Base64-encoded format for certificates. It's enclosed between -----BEGIN CERTIFICATE----- and -----END CERTIFICATE----- markers.
How do I get a certificate from a website?
In most browsers, click the padlock icon in the address bar, view certificate details, and export or copy the certificate in PEM format.
What is a self-signed certificate?
A certificate signed by its own creator rather than a trusted Certificate Authority. These trigger browser warnings but are fine for testing.
Is my certificate data secure?
Yes! All certificate parsing happens in your browser. No data is sent to our servers. Certificates are public information anyway.