SSL Labs TLS Testing Platform

SSL Labs is a non-commercial research project operated by Qualys that provides free tools and documentation for assessing and improving the deployment of SSL, TLS, and Web PKI cryptography across the internet. Founded by security researcher Ivan Ristic, the project has become the de facto standard for server certificate and configuration testing since launching in 2009. The flagship SSL Server Test performs deep analysis of any publicly accessible HTTPS endpoint, evaluating certificate validity and chain, protocol version support from legacy SSL 2.0 through TLS 1.3, cipher suite strength, key exchange parameters, forward secrecy support, and vulnerability exposure including tests for known issues like Heartbleed, POODLE, ROBOT, and DROWN. Each server receives an overall letter grade from A+ to F reflecting its cryptographic posture, with detailed drill-down explanations for each finding. The SSL Client Test examines browser or client TLS implementations to identify supported protocols, cipher preferences, and potential weaknesses. SSL Pulse is a continuous monitoring project that tracks the SSL deployment quality of approximately 150,000 popular websites worldwide, publishing monthly statistics on certificate validity, protocol adoption trends, key sizes, and vulnerability prevalence across the internet. The documentation section provides best practices guides including the popular SSL/TLS Deployment Best Practices and SSL Server Rating Guide, which define the grading methodology. The project also maintains the SSL Client Certificate Support database and contributes to open standards discussions.