Software whose source code is public — free to use, inspect, modify, and share.
Open source is software published under licenses that let anyone read, use, modify, and redistribute the code. It powers essentially everything: the average commercial application is 80–90% open-source components, from web frameworks to cryptography libraries to the container images underneath.
That leverage cuts both ways — you inherit thousands of developers' work, and you inherit their vulnerabilities, licenses, and maintainers' security posture. Safeguard Gold exists to make that inheritance safe: every component in the directory is continuously verified for vulnerabilities, malware, license clarity, and provenance.