Free SSL Checker
Check any website's SSL/TLS certificate in real time: the expiration date, days remaining, hostname coverage, key strength, and the certificate chain.
Checks port 443 by default. Public hosts only.
A Spot Check Is Not Monitoring
This checks one host, once, right now. Certificates expire on a schedule you will forget, and an expired cert takes the whole site down until someone notices. Generator Labs watches every certificate across your domains and internal hosts, then alerts you well before expiry, with the chain and hostname problems flagged before they become outages.
- Continuous expiry, chain, and hostname checks
- Alerts days or weeks before expiry, your choice
- Public and internal CA certificates, with a REST API
- First HTTPS monitor free, then $0.01/host/day
How to Check an SSL Certificate
Enter any hostname above and this SSL certificate checker connects to the host over TLS, reads the certificate the server actually presents, and reports what matters: the expiration date, how many days remain before it expires, whether the certificate covers the hostname you entered, the key type and size, and the full certificate chain. Because it verifies the live certificate rather than a cached copy, it also flags expired, self-signed, and hostname-mismatched certificates that a browser might quietly accept or that fail only on fresh clients. For a TLS checker that grades the server's protocols, ciphers, and known vulnerabilities as well, see TLS Monitoring.
Check an SSL Certificate's Expiration
The most common reason to check an SSL certificate is expiration. An expired certificate fails closed: browsers block the page and API clients refuse to connect. This checker shows the exact expiry date and the days remaining, so you can renew before it lapses. To catch every expiry automatically instead of checking by hand, use SSL certificate monitoring. Mid-renewal? See our guide to renewing an SSL certificate.
SSL Checker FAQ
What the checker reads, and what it can and can't tell you.
What does the SSL checker check?
It connects to the host, reads the certificate the server presents, and reports the expiry date, days remaining, whether the certificate covers the hostname, the key type and size, and the certificate chain.
How do I check when an SSL certificate expires?
Enter the hostname above. The result shows the exact expiry date and how many days remain. To be warned before it happens instead, use SSL certificate monitoring.
Can it check mail servers and other ports?
Yes, on ports that start TLS right away: 443, 8443, and 4433 for web servers, and 465, 993, 995, 990, 989, and 636 for SMTPS, IMAPS, POP3S, FTPS, and LDAPS. STARTTLS services need Certificate Monitoring.
Why does my browser trust a certificate this checker flags?
Browsers often fill in a missing intermediate certificate on their own, so a broken chain can look fine on your desktop and still fail for API clients, mail servers, and phones. This checker reports the chain exactly as the server sends it.
Does it check TLS settings or CAA records?
No, it reads the certificate. TLS Monitoring grades protocols, ciphers, and known vulnerabilities, and our CAA records reference covers checking which CAs may issue for your domain.