What this tool does
Parses X.509 certificates and highlights key fields (subject, issuer, validity, SAN, key usage, signature algorithm).
This page focuses on practical, step‑by‑step usage for **X.509 Certificate Parser**, with clear examples and common pitfalls.
When you should use it
Use it to troubleshoot TLS errors, certificate renewals, and hostname/chain issues.
How to use
- Paste the PEM certificate (-----BEGIN CERTIFICATE----- …).
- Review SANs, validity dates, and key usage.
- Use the parsed output to confirm correct issuance.
Quick example
Example: Verify that a certificate includes the right SAN entries for www and apex domains.
Notes
If you have multiple certs, analyze each and then check the chain separately.
X.509 Certificate Parser
Parse and analyze X.509 certificates in real-time. Decode SSL/TLS certificates, extract details, validate chain, check expiration.
X.509 Certificate Analysis Features
Key Information
Extract RSA, ECC, DSA public key details
Validity Checking
Check expiration dates and validity periods
Fingerprint Generation
SHA1, SHA256, MD5 fingerprints
Chain Validation
Full certificate chain analysis
Understanding X.509 Certificates
X.509 certificates are the standard format for SSL/TLS certificates, used for securing websites, authenticating servers, and establishing encrypted connections.
FAQ
Is X.509 Certificate Parser encryption?
No. It is primarily an analysis/encoding utility. If you need confidentiality, use a real encryption scheme and manage keys properly.
Why does the certificate validate in one place but fail elsewhere?
Most often it’s a chain issue (missing intermediate), hostname mismatch (SAN), or time/expiry problems. Compare the full chain and SAN entries.
Is it safe to paste sensitive data here?
For best security, avoid pasting real secrets (private keys, live tokens, seed phrases). Use test data or work offline, especially for anything that could grant access or move funds.