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SSL Certificate Decoder

Parse PEM-encoded SSL/TLS certificates and extract DER size, SHA-256/SHA-1 fingerprints, trust chain, expiry status, and SAN domains — all client-side.

Browser-BasedResponsive UIPrivacy-First
Privacy: All certificate decoding happens locally in your browser. No PEM data is ever sent to any server.
Quick Examples

PEM Certificate

Bulk Decode
Fetch from Live Server

Makes a real HTTPS connection. No data is stored.

● decoded-summary
$ openssl x509 -text -noout
// Paste a PEM certificate to inspect it.
● dns-hints
// No certificate loaded.

How it works

How SSL Certificate Decoding Works

Use this free SSL certificate decoder to instantly parse PEM-encoded X.509 certificates and extract critical metadata without sending data to any server. The tool extracts DER size, Base64 length, SHA-256 and SHA-1 fingerprints, validity dates, issuer and subject details, and Subject Alternative Names (SANs).

The decoder visualizes the certificate trust chain from Root CA through Intermediate CA to the leaf domain certificate, helping you understand the validation path. A color-coded expiry gauge shows whether your certificate is valid, expiring soon, or expired, with critical alerts for certificates expiring within 30 days.

For developers managing multiple certificates, the bulk decoder supports multi-file upload to parse and compare several PEM certificates simultaneously. Each certificate's SAN domains are displayed as interactive keyword tags for quick reference.

Everything runs locally in your browser using the Web Crypto API. No certificate data ever leaves your device. For production validation, always verify with OpenSSL or your browser's certificate viewer.