SSL Certificate Validator — Chain & Expiry Checker
Paste a PEM certificate to instantly validate expiry, signature algorithm, key strength, SAN presence, and trust chain. Get a clear pass/warn/fail report for each check.
How to Use SSL Certificate Validator — Chain & Expiry Checker
How to Use the SSL Certificate Validator
Step 1: Paste Your PEM Certificate
Copy your certificate in PEM format — the block that starts with -----BEGIN CERTIFICATE----- and ends with -----END CERTIFICATE----- — and paste it into the input field.
To extract a certificate from a running server:
openssl s_client -connect example.com:443 -showcerts </dev/null 2>/dev/null | openssl x509
To view a certificate file:
openssl x509 -in cert.pem -text -noout
Step 2: Review Validation Checks
The tool runs six checks automatically:
- Certificate Expiry — Pass (>30 days), Warning (<30 days), Fail (<14 days or expired)
- Validity Period — Checks the notBefore date is not in the future
- Signature Algorithm — Flags deprecated SHA-1 and MD5; passes SHA-256 and higher
- Key Strength — RSA keys under 2048 bits are flagged as weak
- Subject Alternative Names — Warns if no SANs are present (required by modern browsers)
- Trust Chain — Warns for self-signed certificates
Step 3: Review Certificate Details
Below the checks, see full certificate metadata: subject, issuer, validity dates, key type, signature algorithm, SHA-256 and SHA-1 fingerprints, and all Subject Alternative Names.
Tips
- For leaf (end-entity) certificates, SANs should list all hostnames the cert covers including www and non-www variants
- Self-signed certs are flagged as warnings but are valid for internal use and development environments
- SHA-1 certificates have been deprecated since 2017 and are rejected by Chrome and Firefox
- RSA 2048-bit is the minimum accepted key size; migrate to 4096-bit or ECDSA P-256 for new issuances
Frequently Asked Questions
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