SkillHub indexes 172,000+ AI agent skills from GitHub and makes them instantly discoverable. Skills are SKILL.md files that teach AI agents (Claude Code, OpenAI Codex, GitHub Copilot) specialized capabilities - from PDF manipulation to database queries. Browse by 30+ categories, search with full-text, and install with one command: npx skillhub install Every skill is security-scanned (PASS/WARNING/FAIL). Works with Claude, Codex, and Copilot. Free forever.