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System requirements

  • Operating system: macOS, Linux, or Windows
  • Runtime: Node.js with npm, or Bun
  • Architecture: x64 or ARM64

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Installation methods

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Verify the installation

Confirm Claude Code installed correctly by checking the version:

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Authentication setup

Run Claude Code for the first time and authenticate with your Anthropic account:
Then inside the REPL, run:
The /login command launches an OAuth 2.0 flow in your browser. Sign in with your Anthropic account to complete authentication. On macOS, credentials are stored securely in the system Keychain.
If you already have an ANTHROPIC_API_KEY environment variable set, Claude Code will use it automatically and the /login description changes to “Switch Anthropic accounts”.

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Environment check

After authenticating, run /doctor inside the REPL to verify your environment:
/doctor diagnoses your Claude Code installation and settings, reporting on authentication status, configuration validity, and connectivity.

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Updating

To update Claude Code to the latest version, use the /upgrade command inside the REPL:
Alternatively, re-run the original install command:

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Uninstallation

On macOS, Claude Code stores credentials in the system Keychain. Uninstalling the package does not remove those entries. You can remove them manually via Keychain Access if needed.