Certificate Decoder

1. Paste a PEM-encoded certificate, starting with -----BEGIN CERTIFICATE-----.
2. Details appear automatically, or select “Decode certificate” to run it immediately.
3. Copy the result to your clipboard.

Select “Use example” above to load a sample self-signed certificate.

• The certificate is sent to our API only to decode it; it is never persisted or logged.
• Parsing happens in memory using Node’s built-in certificate parser — no network access, no external process.
• Requests are not included in analytics or error reporting.

• Decodes the leaf (first) certificate only — no chain validation, no trust check.
• A private key or CSR pasted by mistake is rejected, not decoded.

Want to inspect a live host’s certificate instead of one you already have? Try the TLS/Certificate Inspector. Have a certificate request instead of an issued certificate? Try the CSR Decoder. Want expiry severity and structured findings instead of a plain-text dump? Try the Certificate Analyzer.

• Understanding TLS certificate chains and why intermediates matterLeaf, intermediate, and root certificates explained — and why a missing intermediate breaks some clients but not others.