5 free add-ons that make your AI code like a senior
What each one fixes, how to install it, and when to skip it. All checked before we recommend them.
Five free add-ons fix the usual weak spots of AI coding: Agent Skills adds a spec, plan, test and review cycle; Context7 feeds current library docs; Graphify maps big codebases; 21st Magic MCP adds ready-made React components; Strix runs AI security tests on your own app. Start with Agent Skills and Context7.
The 5 at a glance
| Add-on | Fixes | Cost |
|---|---|---|
| Agent Skills | Codes before it plans | Free |
| Context7 | Writes code for old library versions | Free key |
| Graphify | Gets lost in big projects | Free CLI |
| 21st Magic MCP | Plain, ugly UI | Free search, paid AI generation |
| Strix | Ships security holes | Free + open source, uses your own AI credits |
1. Agent Skills (by Addy Osmani)
Adds a full build cycle to Claude Code: spec, plan, build, test, review, ship. Skills are plain markdown, MIT licence.
- Then start any feature with /spec, and finish with /review before you ship.
/plugin marketplace add addyosmani/agent-skills /plugin install agent-skills@addy-agent-skills
2. Context7 (by Upstash)
Gives your AI the current docs for any library (Next.js, Supabase, Stripe…), so it stops writing code for old versions. MIT licence. It sends library names and your question to context7.com, not your code.
- Sign in with the free key when it asks (rate-limited, enough for normal use).
npx ctx7 setup --claude
3. Graphify
Maps your whole codebase into a knowledge graph once, so the AI asks the graph instead of re-reading every file. Parsing runs on your computer.
- Get it from github.com/Graphify-Labs/graphify and follow the README install.
- Worth it for big projects. For a small site, skip it.
- The cloud version is a paid extra you don't need.
4. 21st Magic MCP
Search and add ready-made React + Tailwind components straight from your AI chat.
- Get it from github.com/21st-dev/magic-mcp; it needs a free account key from 21st.dev.
- Searching and adding components is free. AI-generated components need a paid plan.
- Your searches go to 21st.dev.
5. Strix (AI pentest)
AI agents that try to hack your own app in Docker and tell you what to fix. Apache licence.
- Only test apps you own or have written permission to test.
- Needs Docker, and every scan uses your own AI API credits.
- Use pipx (as above), not a curl | bash installer.
pipx install strix-agent export STRIX_TELEMETRY=0
Our order
- Start with Agent Skills and Context7: biggest gain, 5 minutes.
- Add Graphify when a project gets big, 21st for landing pages, Strix before launch.
Questions people ask
Are these add-ons really free?
Agent Skills, Context7 (free key), Graphify (CLI) and Strix are free. 21st Magic MCP is free for searching components; its AI generation is paid. Strix uses your own AI API credits for each scan.
Which one should I install first?
Agent Skills and Context7. They take about 5 minutes and fix the two most common problems: no plan and outdated code.
Is Strix safe to use?
Only point it at apps you own or have written permission to test. Install it with pipx and turn telemetry off with STRIX_TELEMETRY=0.
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