Claude Code

Claude Code — Leaked Source (2026-03-31)
On March 31, 2026, the full source code of Anthropic's Claude Code CLI was leaked via a .map file exposed in their npm registry.

How It Leaked

Chaofan Shou (@Fried_rice) discovered the leak and posted it publicly:
"Claude code source code has been leaked via a map file in their npm registry!"
— @Fried_rice, March 31, 2026

The source map file in the published npm package contained a reference to the full, unobfuscated TypeScript source, which was downloadable as a zip archive from Anthropic's R2 storage bucket.

Quick Setup

Prerequisites

- Bun v1.3+ (the project's runtime)
- Node.js v18+ (for npm package installation)
- An Anthropic API key (set as ANTHROPIC_API_KEY environment variable)

Install & Run

Available Scripts

Environment Variables

Notes

- Some modules from the original source were not included in the leak (Anthropic-internal @ant/* packages, some tools). These have been replaced with stubs that export no-ops.
- The bun:bundle feature flag system is shimmed via a Bun plugin at plugins/bunBundleDev.ts. All flags default to false unless enabled via FEATURE_FLAGS.
- The MACRO.* build-time constants are defined in bunfig.toml and injected by Bun's --define system.

Overview

Claude Code is Anthropic's official CLI tool that lets you interact with Claude directly from the terminal to perform software engineering tasks — editing files, running commands, searching codebases, managing git workflows, and more.

This repository contains the leaked src/ directory.

- Leaked on: 2026-03-31
- Language: TypeScript
- Runtime: Bun
- Terminal UI: React + Ink (React for CLI)
- Scale: ~1,900 files, 512,000+ lines of code

Directory Structure

Core Architecture

1. Tool System (src/tools/)

Every tool Claude Code can invoke is…