SSL Certificate Checker
Check the SSL certificate of any website — expiry date, issuer, validity status and more.
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What this checks
SSL certificate validity, expiry date, issuer organisation, subject CN, SAN domains and signature algorithm.
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Expiry alerts
See exactly how many days until your certificate expires. Get alerted at 30 days remaining — most providers auto-renew at 30 days.
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Why it matters
An expired SSL certificate breaks HTTPS for all visitors, triggers browser security warnings, and can hurt your search rankings.
Frequently Asked Questions
How often should I check my SSL certificate?
Check monthly, or set up monitoring that alerts you 30 days before expiry. Most providers (Let's Encrypt, DigiCert, Sectigo) auto-renew but failures do happen — always verify manually.
What does "Certificate does not match domain" mean?
The SSL certificate was issued for a different domain than the one you're visiting. This triggers browser security warnings. Ensure your certificate covers the exact domain including www and non-www variants.
What is a SAN certificate?
Subject Alternative Name (SAN) certificates cover multiple domains with one certificate. For example, one certificate can cover example.com, www.example.com, and api.example.com.