Beginner21-DayFree

21-Day Claude Code Challenge

A structured 21-day challenge that builds real skills — one day at a time. Learn Claude Code, GitHub, auto mode, and more.

21 days~30–45 min per dayBeginner

21-day roadmap + bonus week

Week 1

Install Claude Code

Install Claude Code and run your first prompt.

The 4-part prompt formula

Learn the formula that gets results every time.

Plan Mode

Make Claude think before it builds.

GitHub branch first

The one habit that saves everything.

Auto Mode

Let Claude build without asking permission.

How to read error messages

Read errors without panicking.

Week 1 Build Day

A complete working homepage from scratch.

Week 2

The CLAUDE.md file

Give Claude permanent context for your project.

What to put in CLAUDE.md

The exact sections that make Claude smarter.

Slash commands

Shortcuts that save you time every session.

The @mention trick

Point Claude at exactly the right file.

Multi-clauding

Run multiple Claude sessions at the same time.

When AI goes wrong

How to recover when Claude breaks things.

Week 2 Build Day

Build a complete second feature from scratch.

Week 3

Skills

Teach Claude your workflow so you never repeat yourself.

Create your own skill

Build a custom skill for your exact project.

Plan Mode for big builds

Use Plan Mode before any complex change.

The loop command

Let Claude iterate without you watching.

Sub-agents

Run parallel tasks across your entire project.

Pre-session workflow

The 5-minute habit before every build session.

Final Build Day

Complete your app. Deploy it. You are done.

Bonus Week — Advanced Skills

What hooks are and how to add one safely

Inspect your real hook setup, add one safe notification hook, and verify it without guessing.

The context window — why Claude goes weird and how to fix it

Spot the warning signs of a full context and fix it in seconds with /compact.

The 5 Golden Rules — the checklist every session needs

Five rules that consistently produce better results and fewer mistakes.

What MCP is and how to inspect or add one connection safely

Inspect existing MCP access, add one safe read-only connection, and verify it before trusting it.

Subagents — how to give Claude Code a specialist job title

Create a reviewer subagent that checks your site through specialist eyes.

Basic safety rules before you let AI touch your files

Five safety rules every non-developer must know before running an AI session.

How to read a diff — and why you must before accepting any change

Read a diff in 30 seconds, catch unexpected changes, and revert only what you did not want.

21-Day Claude Code Challenge | NonDev Apps