Free online SSL certificate checker
🔔 Remind me before SSL expires
Leave your email and we will send a reminder 14 days before this domain's certificate expires. Free, with an unsubscribe link in every email.
Enter a website address to see whether its SSL certificate is valid, when it expires, who issued it and whether browsers trust it. An expired certificate shows scary warnings to your visitors and costs you their trust.
What the SSL checker looks at
The checker connects to the site on port 443 the way a browser does, sending the domain name in SNI, and reads the certificate the server presents. It shows who the certificate is issued for and by whom, the dates it is valid between, how many days are left, which other names it covers and the TLS version agreed for the connection.
Then it checks the two things browsers care about: whether the certificate chains up to a trusted root and whether the name you entered is listed in it. If verification fails, the checker connects a second time without it, so you still see the broken certificate and can tell why it fails instead of getting a bare error.
How to read the SSL result
- Certificate is valid: trusted chain, matching name, within its dates. Nothing to do except keep automatic renewal working.
- Days until expiry: free Let's Encrypt certificates are usually issued for 90 days and renewed about a month before the end. Fewer than 14 days left usually means renewal is failing.
- Issued for a different domain: the server answered with a certificate for another name, often the hosting's default one. The domain is not set up for HTTPS on that server, or DNS points to the wrong server.
- Fails trust verification: the certificate is self-signed, the intermediate certificate is missing, or the issuer is not trusted by browsers.
- Could not connect to the server: nothing answers HTTPS on port 443, or the handshake fails before a certificate is sent.
Related errors and guides
- NET::ERR_CERT_DATE_INVALID: expired certificate
- NET::ERR_CERT_AUTHORITY_INVALID: untrusted issuer
- NET::ERR_CERT_COMMON_NAME_INVALID: wrong name
- ERR_SSL_PROTOCOL_ERROR
- How to renew a Let's Encrypt certificate in cPanel
Frequently asked questions
- Can I get a reminder before my certificate expires?
- Yes. After a check, enter your email in the form under the result. We send one email when 14 days or fewer are left, and every email has an unsubscribe link.
- My browser shows a warning, but the check says the certificate is valid. Why?
- Most often the page loads something over http (mixed content), an antivirus or corporate proxy intercepts HTTPS on your computer, or you are looking at a different name, for example www instead of the bare domain. Run the mixed content check and test the exact name from the address bar.
- Does it test old protocols and weak ciphers?
- No. It shows the TLS version agreed for one modern connection. A full audit of every protocol and cipher the server accepts is outside what this tool does.