Open Claude Code

Open Claude Code is an open-source implementation of the Claude Code CLI, bringing powerful AI-assisted coding capabilities to your terminal. It provides a local interface for interacting with Claude AI models to help you code faster, understand complex codebases, and complete routine development tasks efficiently.

Introduction

Open Claude Code brings the power of Claude AI directly to your development workflow through a terminal interface. It allows you to:

• Get instant help with coding problems without leaving your terminal
• Implement a comprehensive terminal UI for AI interactions using WebAssembly
• Enjoy a rich development experience with advanced layout and rendering capabilities
• Interact with Claude AI in a seamless, intuitive way designed for developers

Features

• Terminal-based UI: A sophisticated terminal interface built with WebAssembly for responsive interactions
• Rich Text Rendering: Support for syntax highlighting, formatting, and complex layouts
• Robust Error Handling: Multi-layered fallback mechanisms ensure the application works even when components fail
• Conversation Context: Maintains conversation history for contextual interactions with Claude
• Command System: Built-in commands for various functions like help, version info, and UI switching
• Mock Implementation: Reliable JavaScript mock implementation when WASM isn't available

Core Capabilities

• Interactive AI Coding Assistant: Have natural language conversations with Claude AI about your code
• Flexible WASM UI Framework: Create rich terminal interfaces with a component-based architecture
• Layout Engine: Flexbox-inspired layout system for creating complex UI layouts in the terminal
• Terminal Rendering: Efficient cell-based rendering with support for colors and text styles
• Event Handling: Process keyboard and mouse events for interactive UI elements

Usage Guide

Installation

# Clone the repository
git clone https://github.com/ruvnet/open-claude-code.git
cd open-claude-code

# Install dependencies
node cli.mjs

# Create a symlink for global access
npm link

Getting Started

1. Run Open Claude Code in your terminal:

   claude

User Guide

This section provides detailed instructions on how to make the most of Open Claude Pro:

• Starting an Interactive Session: Launch the CLI by running claude in your terminal. This opens an interactive environment where you can type queries and commands.
• Common Commands:
  • Use claude to start your session.
  • Run claude commit to create a commit.
  • Execute commands like claude "fix the type errors in the auth module" to automatically address issues.
• Slash Commands: Within the interactive session, use slash commands (e.g., /bug, /clear, /config) for reporting bugs, clearing history, and modifying settings.
• Navigating the Interface: Utilize your terminal's navigation keys to scroll through session history and review past outputs.
• Advanced Features: Benefit from automated Git operations, in-depth code analysis, and custom configurations via commands like claude config.

Report bugs directly with the /bug command or through our GitHub repository.

Before you begin

Check system requirements

Component	Requirements
Operating Systems	macOS 10.15+, Ubuntu 20.04+/Debian 10+, or Windows via WSL
Hardware	4GB RAM minimum
Software	Node.js 18+ git 2.23+ (optional) GitHub or GitLab CLI for PR workflows (optional) ripgrep (rg) for enhanced file search (optional)
Network	Internet connection required for authentication and AI processing

Install and authenticate

Step	Action	Details
1	Install Claude Code	Run in your terminal: npm install -g @anthropic-ai/claude-code
2	Navigate to your project	cd your-project-directory
3	Start Claude Code	Run claude to launch
4	Complete authentication	Follow the one-time OAuth process with your Console account. You'll need active billing at console.anthropic.com.

Core features and workflows

Claude Code operates directly in your terminal, understanding your project context and taking real actions. No need to manually add files to context - Claude will explore your codebase as needed. Claude Code uses claude-3-7-sonnet-20250219 by default.

Security and privacy by design

Your code's security is paramount. Claude Code's architecture ensures:

Feature	Description
Direct API connection	Your queries go straight to Anthropic's API without intermediate servers
Works where you work	Operates directly in your terminal
Understands context	Maintains awareness of your entire project structure
Takes action	Performs real operations like editing files and creating commits

From questions to solutions in seconds

# Ask questions about your codebase
$ claude
> how does our authentication system work?

# Create a commit with one command
$ claude commit

# Fix issues across multiple files
$ claude "fix the type errors in the auth module"

Initialize your project

For first-time users, we recommend:

1. Start Claude Code with claude
2. Try a simple command like summarize this project
3. Generate a CLAUDE.md project guide with /init
4. Ask Claude to commit the generated CLAUDE.md file to your repository

Use Claude Code for common tasks

Claude Code operates directly in your terminal, understanding your project context and taking real actions. No need to manually add files to context - Claude will explore your codebase as needed.

Understand unfamiliar code

> what does the payment processing system do?
> find where user permissions are checked
> explain how the caching layer works

Automate Git operations

> commit my changes
> create a pr
> which commit added tests for markdown back in December?
> rebase on main and resolve any merge conflicts

Edit code intelligently

> add input validation to the signup form
> refactor the logger to use the new API
> fix the race condition in the worker queue

Test and debug your code

> run tests for the auth module and fix failures
> find and fix security vulnerabilities
> explain why this test is failing

Encourage deeper thinking

For complex problems, explicitly ask Claude to think more deeply:

> think about how we should architect the new payment service
> think hard about the edge cases in our authentication flow

Control Claude Code with commands

CLI commands

Command	Description	Example
claude	Start interactive REPL	$ claude
claude "query"	Start REPL with initial prompt	$ claude "explain this project"
claude -p "query"	Run one-off query, then exit	$ claude -p "explain this function"
cat file | claude -p "query"	Process piped content	$ cat logs.txt | claude -p "explain"
claude config	Configure settings	$ claude config set --global theme dark
claude update	Update to latest version	$ claude update
claude mcp	Configure Model Context Protocol servers	$ claude mcp add pyright_lsp

CLI flags

Flag	Description
--print	Print response without interactive mode
--verbose	Enable verbose logging
--dangerously-skip-permissions	Skip permission prompts (only in Docker containers without internet)

Slash commands

Command	Purpose
/bug	Report bugs (sends conversation to Anthropic)
/clear	Clear conversation history
/compact	Compact conversation to save context space
/config	View/modify configuration
/cost	Show token usage statistics
/doctor	Checks the health of your Claude Code installation
/help	Get usage help
/init	Initialize project with CLAUDE.md guide
/login	Switch Anthropic accounts
/logout	Sign out from your Anthropic account
/pr_comments	View pull request comments
/review	Request code review
/terminal-setup	Install Shift+Enter key binding for newlines (iTerm2 and VSCode only)

Manage permissions and security

Claude Code uses a tiered permission system to balance power and safety:

Tool Type	Example	Approval Required	"Yes, don't ask again" Behavior
Read-only	File reads, LS, Grep	No	N/A
Bash Commands	Shell execution	Yes	Permanently per project directory and command
File Modification	Edit/write files	Yes	Until session end

Tools available to Claude

Claude Code has access to a set of powerful tools that help it understand and modify your codebase:

Tool	Description	Permission Required
AgentTool	Runs a sub-agent to handle complex, multi-step tasks	No
BashTool	Executes shell commands in your environment	Yes
GlobTool	Finds files based on pattern matching	No
GrepTool	Searches for patterns in file contents	No
LSTool	Lists files and directories	No
FileReadTool	Reads the contents of files	No
FileEditTool	Makes targeted edits to specific files	Yes
FileWriteTool	Creates or overwrites files	Yes
NotebookReadTool	Reads and displays Jupyter notebook contents	No
NotebookEditTool	Modifies Jupyter notebook cells	Yes

Protect against prompt injection

Prompt injection is a technique where an attacker attempts to override or manipulate an AI assistant's instructions by inserting malicious text. Claude Code includes several safeguards against these attacks:

Safeguard	Description
Permission system	Sensitive operations require explicit approval
Context-aware analysis	Detects potentially harmful instructions by analyzing the full request
Input sanitization	Prevents command injection by processing user inputs
Command blocklist	Blocks risky commands that fetch arbitrary content from the web like curl and wget

Best practices for working with untrusted content:

• Review suggested commands before approval
• Avoid piping untrusted content directly to Claude
• Verify proposed changes to critical files
• Report suspicious behavior with /bug

While these protections significantly reduce risk, no system is completely immune to all attacks. Always maintain good security practices when working with any AI tool.

Configure network access

Claude Code requires access to:

Domain	Purpose
api.anthropic.com	Core API access
statsig.anthropic.com	Statistics and telemetry
sentry.io	Error reporting

Allowlist these URLs when using Claude Code in containerized environments.

Optimize your terminal setup and configure your environment

Claude Code works best when your terminal is properly configured. Follow these guidelines to optimize your experience.

Supported shells

Shell	Support Status
Bash	Supported
Zsh	Supported
Fish	Not currently supported

Themes and appearance

Claude cannot control the theme of your terminal. That's handled by your terminal application. You can match Claude Code's theme to your terminal during onboarding or any time via the /config command.

Line breaks

You have several options for entering linebreaks into Claude Code:

Method	Description
Quick escape	Type \\ followed by Enter to create a newline
Keyboard shortcut	Press Option+Enter (Meta+Enter) with proper configuration

To set up Option+Enter in your terminal:

Terminal	Configuration Steps
Mac Terminal.app	1. Open Settings → Profiles → Keyboard 2. Check "Use Option as Meta Key"
iTerm2 and VSCode terminal	1. Open Settings → Profiles → Keys 2. Under General, set Left/Right Option key to "Esc+"

Tip for iTerm2 and VSCode users: Run /terminal-setup within Claude Code to automatically configure Shift+Enter as a more intuitive alternative.

Notification setup

Never miss when Claude completes a task with proper notification configuration:

Terminal bell notifications

Enable sound alerts when tasks complete:

claude config set --global preferredNotifChannel terminal_bell

For macOS users: Don't forget to enable notification permissions in System Settings → Notifications → [Your Terminal App].

iTerm 2 system notifications

For iTerm 2 alerts when tasks complete:

Step	Action
1	Open iTerm 2 Preferences
2	Navigate to Profiles → Terminal
3	Enable "Silence bell" and "Send notification when idle"
4	Set your preferred notification delay

Note that these notifications are specific to iTerm 2 and not available in the default macOS Terminal.

Handling large inputs

When working with extensive code or long instructions:

Recommendation	Description
Avoid direct pasting	Claude Code may struggle with very long pasted content
Use file-based workflows	Write content to a file and ask Claude to read it
Be aware of VS Code limitations	The VS Code terminal is particularly prone to truncating long pastes

By configuring these settings, you'll create a smoother, more efficient workflow with Claude Code.

Manage costs effectively

Claude Code consumes tokens for each interaction. Typical usage costs range from $5-10 per developer per day, but can exceed $100 per hour during intensive use.

Track your costs

Method	Description
Use /cost	See current session usage
Review cost summary	Displayed when exiting
Check historical usage	In Anthropic Console
Set Spend limits	Control maximum usage

Reduce token usage

Strategy	Description
Compact conversations	Use /compact when context gets large
Write specific queries	Avoid vague requests that trigger unnecessary scanning
Break down complex tasks	Split large tasks into focused interactions
Clear history between tasks	Use /clear to reset context

Costs can vary significantly based on:

Factor	Impact
Size of codebase	Larger codebases require more tokens to analyze
Complexity of queries	Complex questions require more processing
Number of files	More files searched means more tokens used
Length of conversation	Longer history consumes more context
Frequency of compacting	Regular compacting reduces token usage

For team deployments, we recommend starting with a small pilot group to establish usage patterns before wider rollout.

Use with third-party APIs

Connect to Amazon Bedrock

CLAUDE_CODE_USE_BEDROCK=1
ANTHROPIC_MODEL='us.anthropic.claude-3-7-sonnet-20250219-v1:0'

If you don't have prompt caching enabled, also set:

DISABLE_PROMPT_CACHING=1

Requires standard AWS SDK credentials (e.g., ~/.aws/credentials or relevant environment variables like AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY). Contact Amazon Bedrock for prompt caching for reduced costs and higher rate limits.

Connect to Google Vertex AI

CLAUDE_CODE_USE_VERTEX=1
CLOUD_ML_REGION=us-east5
ANTHROPIC_VERTEX_PROJECT_ID=your-project-id

Claude Code on Vertex AI currently only supports the us-east5 region. Make sure your project has quota allocated in this specific region.

Requires standard GCP credentials configured through google-auth-library. For the best experience, contact Google for heightened rate limits.

Development container reference implementation

Claude Code provides a development container configuration for teams that need consistent, secure environments. This preconfigured devcontainer setup works seamlessly with VS Code's Remote - Containers extension and similar tools.

The container's enhanced security measures (isolation and firewall rules) allow you to run claude --dangerously-skip-permissions to bypass permission prompts for unattended operation. We've included a reference implementation that you can customize for your needs.

While the devcontainer provides substantial protections, no system is completely immune to all attacks. Always maintain good security practices and monitor Claude's activities.

Key features

Feature	Description
Production-ready Node.js	Built on Node.js 20 with essential development dependencies
Security by design	Custom firewall restricting network access to only necessary services
Developer-friendly tools	Includes git, ZSH with productivity enhancements, fzf, and more
Seamless VS Code integration	Pre-configured extensions and optimized settings
Session persistence	Preserves command history and configurations between container restarts
Works everywhere	Compatible with macOS, Windows, and Linux development environments

Getting started in 4 steps

Step	Action
1	Install VS Code and the Remote - Containers extension
2	Clone the Claude Code reference implementation repository
3	Open the repository in VS Code
4	When prompted, click "Reopen in Container" (or use Command Palette: Cmd+Shift+P → "Remote-Containers: Reopen in Container")

Configuration breakdown

Component	Purpose
devcontainer.json	Controls container settings, extensions, and volume mounts
Dockerfile	Defines the container image and installed tools
init-firewall.sh	Establishes network security rules

Security features

Feature	Description
Precise access control	Restricts outbound connections to whitelisted domains only (npm registry, GitHub, Anthropic API, etc.)
Default-deny policy	Blocks all other external network access
Startup verification	Validates firewall rules when the container initializes
Isolation	Creates a secure development environment separated from your main system

Customization options

Option	Description
VS Code extensions	Add or remove based on your workflow
Resource allocations	Modify for different hardware environments
Network access	Adjust permissions as needed
Shell configurations	Customize developer tooling

Next steps

Claude Code tutorials Step-by-step guides for common tasks

Reference implementation Clone our development container reference implementation.

License and data usage

Claude Code is provided as a Beta research preview under Anthropic's Commercial Terms of Service.

How we use your data

We aim to be fully transparent about how we use your data. We may use feedback to improve our products and services, but we will not train generative models using your feedback from Claude Code. Given their potentially sensitive nature, we store user feedback transcripts for only 30 days.

Feedback transcripts

If you choose to send us feedback about Claude Code, such as transcripts of your usage, Anthropic may use that feedback to debug related issues and improve Claude Code's functionality (e.g., to reduce the risk of similar bugs occurring in the future). We will not train generative models using this feedback.

Privacy safeguards

We have implemented several safeguards to protect your data, including limited retention periods for sensitive information, restricted access to user session data, and clear policies against using feedback for model training.

For full details, please review our Commercial Terms of Service and Privacy Policy.

License

© Anthropic PBC. All rights reserved. Use is subject to Anthropic's Commercial Terms of Service.