Installation

Claude Code runs as a CLI tool on top of Node.js. Here’s the complete setup for every platform.

Step 1 — Install Node.js

Claude Code requires Node.js v18 or higher. Use v20 LTS or v22 for best results.

Mac (Homebrew):

brew install node

Windows: Download the installer from nodejs.org. During install, check “Add to PATH”.

Linux (Ubuntu/Debian):

curl -fsSL https://deb.nodesource.com/setup_20.x | sudo -E bash -
sudo apt-get install -y nodejs

Verify the install:

node --version   # should print v20.x.x or higher
npm --version    # should print 10.x.x or higher

Step 2 — Install Claude Code

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

Verify:

claude --version

You should see a version number like 1.x.x.

Step 3 — Get an Anthropic API Key

Go to console.anthropic.com
Sign up or log in
Click API Keys in the left sidebar
Click Create Key
Copy the key — it starts with sk-ant-

Important: You only see the key once. Save it somewhere safe.

Step 4 — Set the API Key

Mac / Linux (add to shell profile so it persists):

echo 'export ANTHROPIC_API_KEY=sk-ant-YOUR-KEY-HERE' >> ~/.zshrc
source ~/.zshrc

Or for bash:

echo 'export ANTHROPIC_API_KEY=sk-ant-YOUR-KEY-HERE' >> ~/.bashrc
source ~/.bashrc

Windows (PowerShell, persistent):

[System.Environment]::SetEnvironmentVariable("ANTHROPIC_API_KEY", "sk-ant-YOUR-KEY-HERE", "User")

Then restart your terminal.

For a single session only (any platform):

export ANTHROPIC_API_KEY=sk-ant-YOUR-KEY-HERE

Step 5 — Verify Everything Works

claude --version           # shows version number
echo $ANTHROPIC_API_KEY    # shows your key (Mac/Linux)

Then start your first session:

mkdir test-project && cd test-project
claude

You should see the Claude Code prompt. Type /help to see available commands.

VS Code Integration (Optional but Recommended)

Claude Code integrates with VS Code so you can trigger sessions from the editor.

Open VS Code
Open the Command Palette (Ctrl+Shift+P / Cmd+Shift+P)
Type “Claude Code” — install the extension if prompted
Use Ctrl+Shift+C (Cmd+Shift+C on Mac) to open a Claude Code session in the terminal

Pricing Note

Claude Code uses your Anthropic API key and bills per token. For typical learning sessions (one new app per session, moderate complexity), expect $0.10–$1.00 per session. Claude Sonnet is the default model — more affordable than Claude Opus while still highly capable.

Set a spending limit in the Anthropic console under Billing to avoid surprises.

Troubleshooting

“command not found: claude” after install

npm’s global bin directory isn’t in your PATH. Fix:

npm config get prefix    # shows where global packages are installed
# add that path + /bin to your PATH

“Invalid API key”

Double-check the key in the Anthropic console. Make sure there are no extra spaces or newline characters in the variable.

Windows: PowerShell execution policy

If you see a policy error:

Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser

Next: Your First Session