Quick start

Get Claude Code running in minutes using the pre-built CLI.

The fastest way to use Claude Code is to run the pre-built cli.js that ships inside the npm package. No build step required.

1. Check your Node.js version

   Claude Code requires Node.js 18 or later.

   node --version
   # Should print v18.x.x or higher
   
2. Navigate to the repository root

   The pre-built cli.js lives at the root of the package, alongside package.json.

   cd /path/to/claude-code-source-code
   
3. Verify the CLI works

   node cli.js --version
   # → 2.1.88 (Claude Code)
   
4. Authenticate

   Claude Code needs access to the Anthropic API. Use either method:

   Option 1 — Environment variable (recommended for scripts):

   export ANTHROPIC_API_KEY=sk-ant-...
   

   Option 2 — Interactive login:

   node cli.js login
   

   The login command walks you through the OAuth flow and stores credentials locally.

5. Run a non-interactive query

   Use -p (or --print) to send a single prompt and exit immediately. No interactive session is opened.

   node cli.js -p "Hello Claude"
   

   The response is printed to stdout and the process exits.

6. Start an interactive session

   Run without any flags to open the interactive REPL:

   node cli.js
   

   You’ll see the Claude Code welcome screen. Type your prompt and press Enter. Use /help to list available slash commands.

Key flags

Flag	Description
--version, -v	Print the version string and exit. Zero module loading — the fastest path.
-p, --print	Non-interactive mode. Send one prompt, print the response, and exit.
-c, --continue	Resume the most recent session in the current working directory.
-r, --resume <session-id>	Resume a specific session by ID. Optionally pass a search term to filter the interactive picker.
--model <model-id>	Override the model used for the main agent loop. Accepts aliases (sonnet, opus, haiku) or full IDs.
--output-format <format>	Output format for --print mode: text (default), json, or stream-json.
--max-turns <n>	Maximum number of agentic turns in non-interactive mode.
--dangerously-skip-permissions	Bypass all permission checks. For sandboxed CI/CD pipelines only.
--add-dir <path>	Grant tool access to an additional directory beyond the current working directory.
--allowed-tools <tools...>	Comma/space-separated allowlist of tool names (e.g. "Bash(git:*) Edit").
--disallowed-tools <tools...>	Comma/space-separated denylist of tool names.
--system-prompt <prompt>	Replace the default system prompt with a custom one.
--append-system-prompt <prompt>	Append text to the default system prompt.
--mcp-config <file>	Load MCP server configurations from a JSON file.
--settings <file-or-json>	Load additional settings from a JSON file or inline JSON string.
--bare	Minimal mode: skip hooks, LSP, plugins, attribution, and auto-memory. Auth via ANTHROPIC_API_KEY only.
--no-session-persistence	Disable writing session transcripts to disk (only works with --print).

Example: non-interactive query

ANTHROPIC_API_KEY=sk-ant-... node cli.js -p "List all TypeScript files in ./src that export a default function"

The agent runs, executes whatever tools are needed (glob, read, etc.), prints the final answer, and exits.

Example: resume a previous session

# Continue from where you left off in the current directory
node cli.js --continue

# Resume a specific session by ID
node cli.js --resume sess_abc123

Install globally (optional)

If you want to call claude instead of node cli.js:

npm install -g .
claude --version
# → 2.1.88 (Claude Code)

The -p flag puts Claude Code into non-interactive (headless) mode. This is equivalent to the SDK’s QueryEngine path and is well-suited for scripting and automation.