X.509 Certificate Parser
Decode PEM certificates and inspect key details
Safety note: Only paste public certificates. Avoid sharing private keys.
Input + output
X.509 Certificate Parser
Use this X.509 parser to decode PEM certificates and inspect subjects, issuers, validity dates, and fingerprints. The tool runs entirely in your browser and supports certificate chains.
How to Parse an X.509 Certificate
- Paste your PEM certificate (or chain) into the input box.
- Click Parse Certificate to extract the fields.
- Copy the decoded output for debugging or audits.
Fields You Can Inspect
- Subject and issuer names.
- Validity dates and serial numbers.
- Signature algorithm and public key type.
- Subject Alternative Names (SANs) and fingerprints.
Do This Locally (CLI)
# Parse a certificate with OpenSSL
openssl x509 -in certificate.pem -noout -textFAQ
Does this tool accept certificate chains?
Yes. Paste multiple PEM blocks to parse each certificate.
Is my certificate uploaded?
No. Parsing happens locally in your browser.
Why is the fingerprint unavailable?
If parsing fails or the PEM is malformed, the fingerprint cannot be computed.