Security
Processed locally in your browser — not uploaded
X.509 SSL/TLS Certificate & PEM Decoder
Parse PEM-encoded X.509 TLS/SSL certificates, Certificate Signing Requests (CSR), or Public Keys. Inspect Subject and Issuer details, validity windows, Subject Alternative Names (SANs), key lengths, and SHA-256 / SHA-1 fingerprints locally in your browser.
01
How to use
- Paste a PEM-encoded X.509 Certificate (-----BEGIN CERTIFICATE-----), CSR, or Public Key.
- Click 'Decode Certificate' to parse the Subject, Issuer, Validity window, SANs, and Fingerprints.
- Review expiration status and active days remaining alerts.
- Copy extracted details or SHA-256 fingerprint for verification.
02
Understanding the output
X.509 Certificates wrap cryptographic public keys with identity metadata (Subject, Issuer, Expiration, Subject Alternative Names). Decoding converts Base64 ASN.1 structures into human-readable details entirely within your browser.
03
Common issues & tips
- •Invalid PEM structure: Ensure header (-----BEGIN CERTIFICATE-----) and footer (-----END CERTIFICATE-----) are included.
- •Corrupted Base64 encoding: Make sure no extra spaces or invalid characters are present within the key data block.
Frequently asked questions
- Is my private key or SSL certificate uploaded to any server?
- No. All PEM parsing and cryptographic hashing occur entirely in your local browser engine.