SSL/TLS certificate checker
Check a site's certificate: expiry, issuer and TLS version. Free, no signup.
Never get caught by an expired certificate
WWT checks your certificate, TLS version, uptime, domain expiry and email security every day and warns you well before anything breaks. Free, no credit card.
Start monitoring freeHow to read your SSL/TLS result
Every result starts with the certificate's subject and issuer: who it was issued to, and which certificate authority signed it. The 'valid to' date matters most - once it passes, browsers show a full-page security warning and most visitors leave at once. WWT turns the remaining days red as expiry approaches.
The tool also reports the negotiated TLS version and the full chain of trust, from the leaf certificate up to the root. A chain missing an intermediate certificate often works in one browser and fails in another - exactly the silent problem that continuous monitoring is built to catch before your visitors do.
About SSL/TLS certificates
What is an SSL/TLS certificate?
An SSL/TLS certificate proves a website's identity and encrypts traffic between the browser and the server. Without a valid one, browsers show a security warning.
Why does certificate expiry matter?
When a certificate expires, every visitor gets a security warning and HTTPS breaks - often on a weekend or holiday. Renewing in time avoids outages and lost trust.
Which TLS versions are safe?
Modern best practice is TLS 1.2 and 1.3 only. TLS 1.0 and 1.1 are deprecated and considered insecure.
Which TLS versions are still safe?
TLS 1.2 and TLS 1.3 are current and safe. TLS 1.0 and 1.1 are deprecated and flagged in red - modern browsers and payment standards no longer accept them, so a server still offering them should be updated.
Why does a certificate work in one browser but fail in another?
Usually an incomplete chain: the server sends the leaf certificate but omits an intermediate one. Browsers that cached that intermediate succeed, a fresh device fails. The chain view shows whether every link is present.