Vulnify SSL Checker
Free online SSL checker — test TLS certificate validity, expiry, chain trust, and protocol posture in seconds.
Certificate Validity
Verify that your SSL certificate is valid, properly issued, and not expired.
Expiration Alerts
Get alerts about upcoming certificate expiration to prevent downtime.
Chain Verification
Ensure your certificate chain is complete and properly configured.
Security Analysis
Get a security grade and recommendations to improve your SSL configuration.
Frequently Asked Questions
How do I test a TLS certificate online?
Enter your domain or URL in the Vulnify SSL checker. Quick Check is free with no signup — it grades certificate validity, expiry, chain trust, and TLS protocol support from the public edge.
What is an SSL checker?
An SSL checker tests the TLS certificate and transport configuration served by a website, including validity, expiry, chain presentation, and overall security grade.
Is this SSL checker free?
Yes. Vulnify Quick Check is free with no signup. Enter a domain or URL to review certificate and TLS posture immediately.
How do I check a certificate chain?
The SSL checker inspects whether the server presents the leaf plus required intermediate certificates. Missing intermediates cause partial chain errors in browsers and mobile apps.
What do SSL grades A+ to F mean?
Grades summarize TLS strength. A and A+ indicate modern protocols and strong configuration. Lower grades usually mean expired certificates, weak ciphers, or chain problems that browsers may distrust.
How do I fix SSL certificate errors?
Renew expiring certificates, fix hostname mismatches, complete the intermediate chain, and disable outdated protocols. Use our SSL fix guide for step-by-step remediation.
How often should I check SSL certificates?
Check monthly and before every renewal window. Many certificates expire every 90 days, and an expired certificate triggers browser warnings that block visitors.