SSL Checker

The check shows the certificate's expiration date, who issued it, whether it matches the domain, the signature algorithm, and the key length. Beyond that, it covers the things that actually break certificates in practice.

Incomplete chain

A common and hard-to-notice failure: the server sends only its own certificate and leaves out the intermediate one. On a computer the site still opens, because the browser fetches the missing link by itself. On some phones, in apps, and for search robots it fails with an error.

The owner sees that "everything works" and doesn't understand the complaints. The check says plainly which link is missing.

Address with and without www

Another frequent reason for reports of a "broken" site: the certificate is issued for domain.com while visitors arrive at www.domain.com. Both variants are checked separately.

Not just the certificate

The certificate can be flawless while the site still opens over plain http. So the redirect to https and the HSTS header are checked as well.

The tool also tries each protocol version from TLS 1.0 to 1.3, one handshake per version, and shows which ones the server still accepts. Outdated versions stand out at once.

List of domains

Up to 100 domains can be checked in one run, with the results exported to CSV. That way a single check shows which of your fifty sites has the certificate expiring first.