Wonderstacked

Security

SSL Checker

The SSL Checker inspects a live site's TLS certificate and reports its issuer, subject, validity window and the exact number of days until expiry. It opens a real TLS connection to the host, so you see the certificate the server is actually presenting today.

Last updated · Free, no signup

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What does an SSL certificate checker test?

An SSL checker opens a real TLS connection to a host and reads the certificate the server currently presents. It reports the subject, issuer, Subject Alternative Names, validity dates, and days until expiry, helping diagnose wrong-host certificates, missed renewals, and unexpected certificates at an edge or alternate port.

The server-side probe uses Node's TLS module behind the shared SSRF guard and defaults to port 443. It describes the presented certificate but is not a full browser trust, protocol, cipher, revocation, or vulnerability audit. Results can also differ across CDN edges or SNI configurations.