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Requirements

  • Node.js 18 or higher (node --version to check)
  • Supported platforms: macOS, Linux, Windows (including WSL)
On Windows, running Claude Code natively via WSL (Windows Subsystem for Linux) is the recommended path. Ensure you use a Linux-native Node.js and npm installation inside WSL — not the Windows versions from /mnt/c/. See the Windows note below.

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Install the package

Install @anthropic-ai/claude-code globally so the claude command is available anywhere on your system.

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Install locally in a project

You can also install Claude Code as a local dev dependency and run it via npx:

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Verify the installation

The command prints the installed version and exits.

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Authentication

Claude Code supports several authentication methods. Configure one before your first session. Run claude from any directory. If no credentials are found, Claude Code launches an interactive OAuth flow:
Follow the URL printed in your terminal to log in with your claude.ai account. Claude Code stores the resulting token locally. A Claude subscription is required for this flow. To set up a long-lived token explicitly, run:

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2. API key via environment variable

Set ANTHROPIC_API_KEY in your shell before running claude. Claude Code reads this variable at startup and skips the OAuth flow:
Add the export to your shell profile (~/.bashrc, ~/.zshrc, etc.) to make it permanent.
If ANTHROPIC_API_KEY is set, Claude Code will not use an existing OAuth session. Clear the variable to switch back to OAuth.

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3. Amazon Bedrock

Set CLAUDE_CODE_USE_BEDROCK=1 to route all API calls through Amazon Bedrock. Standard AWS credential resolution applies (environment variables, ~/.aws/credentials, IAM instance roles, etc.):

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4. Google Vertex AI

Set CLAUDE_CODE_USE_VERTEX=1 to route all API calls through Google Vertex AI. Standard Google Cloud credential resolution applies:

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Auto-updater

Claude Code checks for updates automatically and installs them in the background using npm install -g (or bun install -g when running under Bun). The updater requires write access to your global npm prefix directory.

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Disable the auto-updater

Set DISABLE_AUTOUPDATER=1 in your environment to opt out of automatic updates:
You can also add this to your shell profile to make it permanent. To update manually when the auto-updater is disabled, run:

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Windows and WSL

On Windows, the auto-updater requires a Linux-native npm installation. If Claude Code detects that npm is being resolved from the Windows path (e.g. /mnt/c/...), the update will fail. Install Node.js inside your Linux distribution and ensure the Linux npm appears first in PATH:

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System CA certificates

Claude Code uses the system’s TLS stack for all API calls. In environments with custom or corporate CA certificates (e.g. TLS-intercepting proxies), you may need to supply additional certificates.

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NODE_EXTRA_CA_CERTS

Point NODE_EXTRA_CA_CERTS to a PEM-format CA bundle file. Claude Code appends these certificates to the built-in Mozilla root store:

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—use-system-ca

Pass --use-system-ca in NODE_OPTIONS to use the operating system’s CA store instead of the bundled Mozilla roots:
You can combine both options: --use-system-ca selects system CAs as the base, and NODE_EXTRA_CA_CERTS appends additional certificates on top.
If you see SSL certificate errors mentioning *.anthropic.com, set NODE_EXTRA_CA_CERTS to your corporate CA bundle path or ask your IT team to allowlist the Anthropic API endpoints.

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Configuration directory

Claude Code stores its configuration, session data, and credentials in ~/.claude/ by default. Override this with the CLAUDE_CONFIG_DIR environment variable:

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Uninstall

Remove the global package with the package manager you used to install it:
You can also remove the configuration directory if you want to delete stored credentials and settings: