Check a certificate's expiry, covered names, chain and supported TLS versions.
SSL and Security tools
Inspect certificates and the security headers your server sends to browsers.
Review HSTS, CSP, X-Frame-Options and other headers, with config to fix gaps.
Keeping HTTPS working
Certificates
Most certificates now last 90 days and renew automatically, which works until it quietly stops. The SSL Checker shows days left, the names covered and whether the chain is complete. A missing intermediate certificate is a common reason a site works on your laptop but fails on some phones.
Security headers
A few response headers tell browsers to block common attacks: HSTS stops downgrades to plain HTTP, Content-Security-Policy limits which scripts can run, and others prevent clickjacking and data leaks. The Security Headers Checker grades what your site sends and gives you the lines to add.
Mail servers too
Certificates matter for email as well. The SSL Checker can test ports 465, 993 and 995, so you can confirm your mail server's certificate before users see warnings in their email apps.