SSL Checker

The SSL Checker is a free tool that runs a full TLS handshake analysis against any domain's live server — checking certificate validity and chain of trust, which protocol versions and cipher suites it supports, whether HSTS is enabled, and testing for a set of well-known vulnerabilities like Heartbleed, POODLE, and FREAK. Those results are combined into an industry-standard A+ through F grade, so instead of a simple valid or invalid verdict, you get a genuine picture of how secure a domain's HTTPS setup actually is.

It exists because a valid certificate alone doesn't guarantee a strong setup — a site can have a perfectly legitimate certificate while still supporting outdated, insecure protocols that undermine the encryption in practice. Whether you're verifying a certificate renewal went smoothly, checking a server for known vulnerabilities before it worries a security-conscious client, or just confirming a domain's TLS configuration is genuinely current, this scan surfaces the details that certificate validity alone won't show.

When you submit a domain, the tool connects directly to its live server and performs a full TLS handshake analysis — validating the certificate and its chain of trust, testing which protocol versions (from outdated TLS 1.0 up through current versions) and cipher suites the server accepts, confirming whether HSTS is enabled, and running checks for a set of well-known vulnerabilities including Heartbleed, POODLE, FREAK, and Logjam. Each result feeds into the same A+ through F grading scale used by industry-standard SSL testing services.

A full analysis involves testing dozens of protocol and cipher combinations against the live server, which can realistically take 20 to 90 seconds for a domain that hasn't been scanned recently. Once scanned, a domain's result is cached for a period of time, so re-checking the same domain shortly after usually returns instantly rather than re-running the full handshake analysis from scratch.

• A valid certificate isn't the whole story. A site can have a perfectly valid certificate while still supporting outdated, insecure protocols — the grade accounts for both, not just certificate validity alone.
• Watch your renewal date closely. Most modern certificates last 90 days to a year, so set a reminder well before expiry — an expired cert breaks HTTPS entirely and triggers browser warnings for every visitor.
• Old vulnerabilities still get checked for a reason. Flaws like Heartbleed and POODLE are old, but servers running outdated software can still be exposed, so it's worth confirming rather than assuming they've been patched.
• Don't ignore a weak cipher suite warning even with a valid certificate. Outdated cipher configurations can undermine an otherwise properly issued certificate, quietly weakening the actual encryption strength visitors get.