SSL Checker

Enter a URL to inspect the TLS certificate the site presents: validity and expiry countdown, subject and issuer, SANs, negotiated protocol and cipher, and the certificate chain.

What does a certificate check tell you?

The checker performs a TLS handshake only — it never loads the page — and reports the certificate the server presents: whether it is valid and trusted, when it expires, who issued it, which domains it covers, the negotiated protocol and cipher, and the chain from leaf to root. A broken certificate is reported with the concrete reason (expired, not yet valid, hostname mismatch, untrusted issuer) even though the handshake failed.

Why check a certificate?

  • Catch expiry early: certificates that lapse take the site down for visitors and break APIs.
  • Verify deployments: make sure the new certificate was installed and is trusted.
  • Diagnose errors: the failure type (expired, mismatch, unknown authority) points at the fix.
  • Check third parties: see what a host presents before you send credentials there.

What you get

One instant check with an expiry-first result: a validity verdict with a days-remaining countdown, issued to/issued by, the validity window, SANs, protocol/cipher, and the chain — or the exact reason the certificate failed, with whatever facts the server sent. The probe contacts the validated host only and never fetches the page.

Related tools