SSL / TLS Checker
One of the free tools from KinetixSEO, an SEO and AI-citation (GEO) checker. Runs a real TLS handshake against any domain and reports certificate validity, expiry, chain and hostname trust, protocol version, and key strength — the details that quietly break a browser's padlock icon or a hard security warning.
Frequently asked questions
What does this SSL/TLS checker actually look at?
It performs a real TLS handshake against your domain and reports the certificate's issuer, subject, validity window, days until expiry, whether the certificate chain and hostname validate, the negotiated TLS protocol version, and the key algorithm and strength (RSA/EC bits).
Why does certificate expiry matter for SEO?
An expired certificate makes browsers show a hard security warning before visitors ever see your page, which tanks click-through and conversion instantly — and search engines treat a broken HTTPS connection as a strong negative trust signal.
What is a "legacy protocol" warning?
TLS 1.0 and 1.1 (and SSL 2.0/3.0) are deprecated and no longer considered secure — modern browsers are phasing out support for them. If your server still negotiates one of these, upgrade your TLS configuration to require TLS 1.2 or 1.3.
What counts as a "weak" key?
RSA and DSA keys under 2048 bits, and EC keys under roughly 224 bits (or on a small number of deprecated named curves), are considered too weak for modern security standards and should be reissued with a stronger key.
Is this the same certificate check as SSL Labs?
It checks the same fundamentals — validity, chain trust, hostname match, protocol and key strength — in a single instant pass. SSL Labs runs a much deeper multi-minute analysis (cipher suite ordering, known vulnerability scans); use this tool for a fast first look, not a full security audit.
This is one check from KinetixSEO's full SEO/GEO audit. Want the complete picture — Core Web Vitals, AI-citation readiness, technical SEO health, and tailored fixes? Run the free full checker.