OpenZeppelin is the industry standard for smart contract security. Founded in 2017, it provides open-source contract libraries, security audits, and the Defender monitoring platform, with $50M+ raised.
Nmap (Network Mapper) is the world's most widely used open source network scanning and security auditing tool, created and maintained by Gordon Lyon (Fyodor), with 600+ NSE scripts and 40+ probe techniques as the de facto standard for network discovery.
SSL Config is an online SSL/TLS configuration checker and security diagnostic tool that helps server administrators detect and optimize SSL security configurations, completely free to use.