Installation

Install Claude Code on macOS, Linux, or Windows (via WSL). Requires Node.js 18 or higher.

Requirements

• Node.js 18 or higher — Claude Code checks the Node.js version at startup and exits with an error if it is below 18.
• npm — included with Node.js.

Check your current version:

node --version
npm --version

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Install Claude Code

Install globally with npm:

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

After installation, verify it works:

claude --version

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Platform-specific notes

macOS

npm global installs work out of the box on macOS. If you get a permissions error when running npm install -g, you have two options:

Option A: Fix npm permissions (recommended)

Configure npm to use a directory in your home folder:

mkdir -p ~/.npm-global
npm config set prefix ~/.npm-global

Add the following to your shell profile (~/.zshrc or ~/.bash_profile):

export PATH=~/.npm-global/bin:$PATH

Then reload your profile and install:

source ~/.zshrc
npm install -g @anthropic-ai/claude-code

Option B: Use a Node version manager

Tools like nvm or fnm install Node.js in your home directory, which avoids global permission issues entirely:

# Using nvm
nvm install --lts
nvm use --lts
npm install -g @anthropic-ai/claude-code

Linux

On most Linux distributions, npm install -g requires either sudo or a corrected npm prefix. Using sudo is not recommended because it can create permission problems later.

Recommended: Use a Node version manager

# Install nvm
curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.40.0/install.sh | bash

# Reload your shell, then install Node.js
nvm install --lts
nvm use --lts

# Install Claude Code
npm install -g @anthropic-ai/claude-code

Alternative: Fix npm global prefix

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

Windows (WSL)

Claude Code runs on Windows through the Windows Subsystem for Linux (WSL). Running it directly in Command Prompt or PowerShell is not supported.

Step 1: Install WSL

Open PowerShell as Administrator and run:

wsl --install

Restart your machine when prompted. This installs WSL 2 with Ubuntu by default.

Step 2: Open a WSL terminal

Launch Ubuntu from the Start menu, or run wsl from PowerShell.

Step 3: Install Node.js inside WSL

curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.40.0/install.sh | bash
source ~/.bashrc
nvm install --lts
nvm use --lts

Step 4: Install Claude Code

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

Always run claude from within your WSL terminal, not from Windows CMD or PowerShell. Your project files should live inside the WSL filesystem (e.g., ~/projects/) for best performance. Accessing Windows files via /mnt/c/... works but is slower.

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Updating

Update Claude Code to the latest version with:

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

Or use Claude Code’s built-in update command:

claude update

To check what version you’re running:

claude --version

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Uninstalling

Remove Claude Code with:

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

This removes the claude binary. Your configuration files in ~/.claude/ are not removed automatically. To delete them:

rm -rf ~/.claude

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Troubleshooting

'claude' command not found after installation

This usually means the npm global bin directory is not on your PATH.

Find where npm installs global binaries:

npm config get prefix

The bin subdirectory of that path needs to be on your PATH. For example, if the output is /home/you/.npm-global, add this to your shell profile:

export PATH=/home/you/.npm-global/bin:$PATH

Reload your shell (source ~/.zshrc or open a new terminal) and try again.

Node.js version is below 18

Claude Code requires Node.js 18 or higher. If you see this error at startup:

Error: Claude Code requires Node.js version 18 or higher.

Upgrade Node.js using your version manager:

# nvm
nvm install --lts
nvm use --lts

# fnm
fnm install --lts
fnm use --lts

Or download the latest LTS release from nodejs.org.

Permission denied when running npm install -g

Do not use sudo npm install -g — it can leave files owned by root and cause further issues. Instead, fix your npm prefix to point to a user-writable directory:

mkdir -p ~/.npm-global
npm config set prefix ~/.npm-global
export PATH=~/.npm-global/bin:$PATH
npm install -g @anthropic-ai/claude-code

Add the export PATH line to your shell profile so it persists across sessions.

Authentication fails on first run

If the browser-based OAuth flow fails or you cannot use a browser, set your API key directly as an environment variable instead:

export ANTHROPIC_API_KEY=sk-ant-...
claude

You can add this to your shell profile to make it permanent. API keys are available in the Anthropic Console.

Running inside Docker or a CI environment

In non-interactive environments, authenticate with an API key via the environment variable:

export ANTHROPIC_API_KEY=sk-ant-...

Use the -p flag to run non-interactively:

claude -p "run the test suite and report any failures"

If you need Claude Code to operate without permission prompts in a sandboxed container, use the --dangerously-skip-permissions flag. This flag only works in environments that pass Claude Code’s sandbox safety checks (no internet access and not running as root outside a container).