# Free open-source agent skills and plugins

> Skill packs, plugins and prompt libraries that extend Claude Code, Codex, Cursor and other AI coding agents.

Free tools: popular open-source projects that do not replace a paid product.

## Projects, ranked
1. [ECC](https://repoquarry.dev/projects/ecc.md): Large plugin of agents, skills, hooks, rules and memory for Claude Code, with native Codex and Qoder plugins and partial adapters for other agents. Commercial use: Confirmed.
2. [Superpowers](https://repoquarry.dev/projects/superpowers.md): Skill library for coding agents that walks them through brainstorming, planning, test-driven development, subagent work and code review. Commercial use: Confirmed.
3. [Agent Skills (Addy Osmani)](https://repoquarry.dev/projects/addyosmani-agent-skills.md): Addy Osmani's pack of 25 engineering skills and slash commands that take a coding agent from spec and plan through tests, review and shipping. Commercial use: Confirmed.
4. [Skills For Real Engineers (Matt Pocock)](https://repoquarry.dev/projects/mattpocock-skills.md): Matt Pocock's small, composable agent skills for engineering work, such as grilling sessions, TDD, bug diagnosis, specs and code review. Commercial use: Confirmed.
5. [Impeccable](https://repoquarry.dev/projects/impeccable.md): Frontend design skill for AI coding agents with 24 commands, live browser iteration and a CLI that flags common AI-generated design mistakes. Commercial use: Confirmed.
6. [AI Job Search](https://repoquarry.dev/projects/ai-job-search.md): Claude Code workflow for job seekers that scores job postings, tailors a LaTeX CV and cover letter, and preps you for interviews. Commercial use: Confirmed.
7. [Diagram Design](https://repoquarry.dev/projects/diagram-design.md): Agent skill that has your coding agent draw 45 types of diagram as one self-contained HTML and SVG file, styled to match your brand. Commercial use: Confirmed.
8. [Scientific Agent Skills](https://repoquarry.dev/projects/scientific-agent-skills.md): Pack of 177 science and research skills for AI coding agents, covering biology, chemistry, medicine, physics and data analysis. Commercial use: Confirmed.
9. [text-to-cad](https://repoquarry.dev/projects/text-to-cad.md): Plugin for AI coding agents that generates 3D CAD models (STEP, GLB, STL, 3MF), runs manufacturing checks and makes engineering drawings. Commercial use: Confirmed.
10. [Claude Code Plugins Directory](https://repoquarry.dev/projects/claude-plugins-official.md): Anthropic's curated marketplace of Claude Code plugins, with its own plugins and reviewed third-party ones. Commercial use: Partial.
11. [Claude for Financial Services](https://repoquarry.dev/projects/financial-services.md): Anthropic's reference agents, skills and data connectors for banking, equity research, private equity and fund admin in Claude. Commercial use: Confirmed.
12. [Cursor Plugins](https://repoquarry.dev/projects/cursor-plugins.md): Cursor's official marketplace plugins - skills, rules and MCP connections for dev workflows and SaaS apps such as GitHub, Gmail and Salesforce. Commercial use: Confirmed.
13. [Android skills](https://repoquarry.dev/projects/android-skills.md): Google's official Agent Skills for Android development, for coding agents such as Gemini, Claude Code and Codex. Commercial use: Confirmed.
14. [Newsjack](https://repoquarry.dev/projects/newsjack.md): PR skills for AI agents that find news to react to, draft pitches and headlines, fact-check, and build media lists. Commercial use: Confirmed.
15. [Ponytail](https://repoquarry.dev/projects/ponytail.md): Makes your AI agent think like the laziest senior dev in the room. The best code is the code you never wrote. Commercial use: Unknown.
16. [Graphify](https://repoquarry.dev/projects/graphify.md): Turn any codebase, with its docs, SQL schemas, configs, and PDFs, into a queryable knowledge graph. A /graphify skill for Claude Code, Cursor, Codex, and Gemin… Commercial use: Unknown.
17. [SwiftUI-Agent-Skill](https://repoquarry.dev/projects/swiftui-agent-skill.md): SwiftUI agent skill for Claude Code, Codex, and other AI tools. Commercial use: Unknown.
18. [Knowledge-work-plugins](https://repoquarry.dev/projects/knowledge-work-plugins.md): Open source repository of plugins primarily intended for knowledge workers to use in Claude Cowork Commercial use: Unknown.
19. [Security-audit-skill](https://repoquarry.dev/projects/security-audit-skill.md): A coding-agent skill for multi-phase security audits with independently verified, machine-readable findings Commercial use: Unknown.
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Source: RepoQuarry (https://repoquarry.dev/categories/agent-skills). Data licence: CC BY 4.0. Quotes are from project documentation and belong to their authors.