SSL Certificate Decoder
Decode and view SSL/TLS certificate details
Certificate is valid
Subject
Issuer
Validity
Not Before -
Not After -
Days Remaining -
Key Information
Algorithm -
Key Size -
Serial Number -
Version -
Subject Alternative Names (SAN)
None
Fingerprints
SHA-256 -
SHA-1 -
Privacy & Security
- All certificate decoding happens locally in your browser
- Your certificates never leave your device or get sent to any server
- Safe for analyzing production certificates
- Works offline once the page is loaded
About SSL Certificate Decoder
This tool allows you to decode and view the details of SSL/TLS certificates in PEM format. You can analyze certificate information including the subject, issuer, validity period, public key details, and extensions like Subject Alternative Names (SAN).
What Information Can You See?
- Subject: The entity the certificate is issued to (domain, organization)
- Issuer: The Certificate Authority that issued the certificate
- Validity: When the certificate becomes valid and when it expires
- Public Key: Algorithm and key size information
- SAN: Additional domain names covered by the certificate
- Fingerprints: SHA-256 and SHA-1 hashes for verification
Common Use Cases
- Verifying certificate details before installation
- Checking certificate expiration dates
- Debugging SSL/TLS connection issues
- Auditing certificates in your infrastructure
- Verifying certificate chain information
Certificate Formats
This tool accepts certificates in PEM format, which is the most common format for SSL certificates. PEM files are Base64 encoded and typically have headers like "-----BEGIN CERTIFICATE-----".