How to Install Claude Code

Claude Code is Anthropic's official CLI for AI-assisted development. Unlike browser-based tools, it runs directly in your terminal alongside your existing workflow — your editor, your Git, your shell. This guide walks you through every step from zero to your first AI-assisted coding session.

Prerequisites

Before installing Claude Code, make sure you have two things in place.

1. Node.js 18 or Later

Claude Code requires Node.js 18+. Check what you have:

node --version

If you see v18.x.x or higher, you're good. If not, install Node.js from nodejs.org or via a version manager:

# Using nvm (recommended)
nvm install 20
nvm use 20

# On macOS with Homebrew
brew install node

2. An Anthropic API Key

Claude Code calls Anthropic's API, so you need an account and API key.

1. Go to console.anthropic.com
2. Sign up or log in
3. Navigate to API Keys → Create Key
4. Copy the key — you'll need it during setup

Keep this key private. Never commit it to a repository.

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Installation

Option A: npm (All Platforms)

The standard installation method works on macOS, Linux, and Windows:

npm install -g @anthropic-ai/claude-code

Verify the installation succeeded:

claude --version

You should see something like claude-code/1.x.x.

Option B: Homebrew (macOS / Linux)

If you prefer Homebrew:

brew install anthropic/tap/claude-code

Option C: Windows (via npm in PowerShell or WSL)

On Windows, use either PowerShell with Node.js installed, or Windows Subsystem for Linux (WSL). WSL is recommended for a smoother experience:

# In PowerShell
npm install -g @anthropic-ai/claude-code

# In WSL (Ubuntu)
npm install -g @anthropic-ai/claude-code

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First Run and Authentication

Once installed, run Claude Code from any directory:

claude

On first launch, Claude Code will prompt you for your API key:

Welcome to Claude Code!
Please enter your Anthropic API key: sk-ant-...

Enter the key you created earlier. Claude Code stores it securely in your system's credential store — you won't be asked again.

Alternatively, set it as an environment variable before running:

export ANTHROPIC_API_KEY=sk-ant-your-key-here
claude

To make this permanent, add the export line to your shell profile (~/.zshrc, ~/.bashrc, or equivalent).

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Basic Configuration

Claude Code works out of the box with sensible defaults, but a few settings are worth configuring early.

Project-Level Config: CLAUDE.md

In any project, create a CLAUDE.md file at the root. Claude reads this file automatically when you start a session in that directory:

# My Project

## Stack
- Next.js 14, TypeScript, Tailwind CSS
- Supabase for database and auth
- Deployed on Vercel

## Conventions
- Use named exports, not default exports
- Prefer `const` over `let`
- All components go in `src/components/`

This file tells Claude about your project without you having to explain it every session.

Global Config

Claude Code also reads ~/.claude/CLAUDE.md for global preferences that apply to every project:

mkdir -p ~/.claude
touch ~/.claude/CLAUDE.md

Add global rules here — your preferred code style, things Claude should always or never do, output format preferences.

Skills Directory

The ~/.claude/skills/ directory is where Claude Code skills live. Skills are markdown files that give Claude domain-specific expertise — more on this in a moment:

mkdir -p ~/.claude/skills

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Verifying It Works

Let's do a quick sanity check. Navigate to any project directory and run:

cd ~/your-project
claude

At the > prompt, type:

What files are in this project?

Claude will scan the directory and give you a summary. If it responds intelligently about your files, everything is working.

Try a real task:

Review the main entry point and suggest any improvements.

Claude will read the file, analyze it, and respond with concrete suggestions. That's it — you're using AI-assisted development.

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Installing Skills (Optional but Recommended)

Claude Code skills extend what Claude knows. A react-expert skill makes Claude follow React 18 best practices automatically. A typescript-pro skill enforces strict TypeScript patterns. Skills live in ~/.claude/skills/ as markdown files.

To install a skill pack:

# Download and extract a skills ZIP
unzip superskills.zip -d ~/.claude/skills/

# Verify skills are in place
ls ~/.claude/skills/

Restart Claude Code after adding new skills — they're loaded at startup.

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Common Issues

"command not found: claude" The npm global bin directory isn't in your PATH. Run npm bin -g to find it and add it to your ~/.zshrc or ~/.bashrc.

"API key invalid" Double-check the key in console.anthropic.com. Make sure you're copying the full key including the sk-ant- prefix.

Slow first response The first message in a session can take a few seconds as Claude loads your project context. Subsequent messages are faster.

Permission errors on macOS If npm install fails with permissions errors, avoid sudo. Instead, configure npm to use a user-writable directory:

mkdir ~/.npm-global
npm config set prefix '~/.npm-global'
echo 'export PATH=~/.npm-global/bin:$PATH' >> ~/.zshrc
source ~/.zshrc
npm install -g @anthropic-ai/claude-code

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What's Next?

Now that Claude Code is running, here's how to get the most out of it:

• Add a CLAUDE.md to every project — context is everything
• Install skills to give Claude domain-specific expertise
• Use it for real tasks — code reviews, refactoring, debugging, writing tests
• Explore the --print flag for non-interactive use in scripts

The difference between a basic Claude Code setup and a great one is almost entirely about context: what you tell Claude, and which skills you've installed.

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Ready to level up? Get all 139 SuperSkills for $50 — one ZIP file, drop it into ~/.claude/skills/, and Claude Code becomes expert-level across 20 domains.