How to Install Claude Code: npm Setup, Auth & First Run

Steps

1. 01

   Install Claude Code — the native installer (what Anthropic recommends)

   Anthropic's setup page lists the native installer as the recommended method (checked 2026-10-01). It needs no Node.js, and native installs update themselves in the background. Pick the line for your shell; Homebrew and WinGet are the package-manager alternatives (those two do not auto-update). Open a new terminal window when it finishes.

   # macOS, Linux, WSL
   curl -fsSL https://claude.ai/install.sh | bash
   
   # Windows PowerShell
   irm https://claude.ai/install.ps1 | iex
   
   # Homebrew (macOS/Linux)
   brew install --cask claude-code
   
   # WinGet (Windows)
   winget install Anthropic.ClaudeCode

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2. 02

   Or install Claude Code with npm

   If you prefer npm, this is the command. Per Anthropic's docs the npm package installs the same native binary as the standalone installer, pulled in through a per-platform optional dependency, so your package manager must allow optional dependencies. In our 2026-09-04 run the postinstall step (install.cjs) took roughly 20 seconds. The -g flag puts the claude command in your global npm bin directory.

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

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3. 03

   Verify the install

   After install completes, confirm the binary is on your PATH by checking the version. If the command is not found, see the PATH troubleshooting section below.

   claude --version

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4. 04

   Authenticate — Option A: Anthropic account (Claude Pro / Max / Team)

   Run claude with no arguments to start the interactive shell. On first launch it will prompt you to authenticate. Choose the 'Login with Anthropic account' flow. This opens a browser window where you authorize Claude Code against your existing Claude Pro, Max, or Team subscription. Once authorized, account metadata is saved to ~/.claude.json and the OAuth token is stored in your OS keychain (under 'Claude Safe Storage'). Subsequent launches skip the browser step automatically. This is the recommended path if you already pay for Claude at claude.ai.

   claude

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5. 05

   Authenticate — Option B: ANTHROPIC_API_KEY

   If you prefer API key authentication (useful for CI, shared machines, or pay-per-token billing), set the environment variable before running. Export it in your shell profile (~/.zshrc, ~/.bashrc, etc.) to make it permanent. With ANTHROPIC_API_KEY set, Claude Code asks you once to approve the key instead of opening a browser (Anthropic's setup docs, checked 2026-10-01).

   export ANTHROPIC_API_KEY="sk-ant-..."
   claude

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6. 06

   Run Claude Code interactively

   With no arguments, claude opens a persistent interactive session. You can type multi-line prompts, ask it to edit files, run commands, and use slash commands inside the REPL. Type /help inside the session to see available slash commands. Press Ctrl+C or type /exit to quit.

   claude

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7. 07

   Run a one-shot prompt (non-interactive / scripting mode)

   For scripting, CI pipelines, or quick one-off tasks, pass the prompt directly. The -p flag (--print) runs the prompt without entering the interactive shell and prints the result to stdout. You can also pass a prompt as a bare positional argument for convenience.

   # Using the --print flag (non-interactive)
   claude -p "Explain what this repo does"
   
   # Or as a positional argument
   claude "List all TODO comments in src/"

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8. 08

   Run Claude Code inside your IDE

   Claude Code is a terminal tool — it runs in any integrated terminal. Open your IDE's built-in terminal (VS Code: Ctrl+`, Cursor: same), navigate to your project directory, and run claude. No IDE plugin is required for this. If you want an integrated panel instead, Anthropic also ships a VS Code extension and a JetBrains plugin. The agent reads and edits files directly from the working directory.

   # Navigate to your project first
   cd /path/to/your/project
   claude

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9. 09

   Persist your API key in your shell profile (optional but recommended)

   To avoid exporting the key every session when using API key auth, add the export line to your shell profile. Replace ~/.zshrc with ~/.bashrc if you use bash.

   echo 'export ANTHROPIC_API_KEY="sk-ant-..."' >> ~/.zshrc
   source ~/.zshrc

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Troubleshooting

command not found: claude after npm install -g

npm's global bin directory is not in your PATH. Find it with: npm config get prefix — then append /bin to that path and add it to your PATH. Example for macOS/Linux: add export PATH="$(npm config get prefix)/bin:$PATH" to your ~/.zshrc or ~/.bashrc, then run source ~/.zshrc. On macOS with Homebrew-managed Node, the prefix is often /opt/homebrew.

npm EBADENGINE warning about Node >=22 during install

The floor moved: v2.1.183 declared Node >=18, and since v2.1.198 the npm package declares Node 22 or later. Per Anthropic's setup docs (checked 2026-10-01), on an older Node npm prints an EBADENGINE warning rather than failing — the install completes and claude still runs, because the package only links a native binary that does not use Node at runtime. To get rid of the warning, upgrade Node (nvm install --lts && nvm use --lts) or switch to the native installer, which does not need Node at all.

npm install fails with EACCES permission denied on global install

You are trying to write to a system-owned directory. The clean fix is to configure npm to use a user-writable prefix: mkdir -p ~/.npm-global && npm config set prefix ~/.npm-global, then add export PATH="$HOME/.npm-global/bin:$PATH" to your profile. Alternatively, use nvm which installs Node in your home directory and avoids this entirely. Do not use sudo npm install -g as it can corrupt permissions.

Authentication loop — browser opens but Claude Code never recognizes the login

This usually means the callback URL was blocked or the browser closed before the token was written. Try again in a browser that is not blocking redirects. If you are on a headless server or CI environment, switch to ANTHROPIC_API_KEY authentication instead — set the env var and run claude without the interactive auth flow.

MCP server shows as 'pending-approval' and tools are not available

Claude Code requires explicit approval of MCP servers defined in a project's .mcp.json file before it exposes their tools. When prompted inside the interactive session, choose to approve the server. If you accidentally rejected it, run claude mcp reset-project-choices inside the project directory, then restart claude to see the approval prompt again.