OpenClaude

Use Claude Code with any LLM — not just Claude.

OpenClaude is a fork of the Claude Code source leak (exposed via npm source maps on March 31, 2026). We added an OpenAI-compatible provider shim so you can plug in GPT-4o, DeepSeek, Gemini, Llama, Mistral, or any model that speaks the OpenAI chat completions API. It now also supports the ChatGPT Codex backend for codexplan and codexspark, and local inference via Atomic Chat on Apple Silicon.

All of Claude Code's tools work — bash, file read/write/edit, grep, glob, agents, tasks, MCP — just powered by whatever model you choose.

Start Here

If you are new to terminals or just want the easiest path, start with the beginner guides:

If you want source builds, Bun workflows, profile launchers, or full provider examples, use:

Advanced Setup

Beginner Install

For most users, install the npm package:

npm install -g @gitlawb/openclaude

The package name is @gitlawb/openclaude, but the command you run is:

openclaude

If you install via npm and later see ripgrep not found, install ripgrep system-wide and confirm rg --version works in the same terminal before starting OpenClaude.

Fastest Setup

Windows PowerShell

npm install -g @gitlawb/openclaude

$env:CLAUDE_CODE_USE_OPENAI="1"
$env:OPENAI_API_KEY="sk-your-key-here"
$env:OPENAI_MODEL="gpt-4o"

openclaude

macOS / Linux

npm install -g @gitlawb/openclaude

export CLAUDE_CODE_USE_OPENAI=1
export OPENAI_API_KEY=sk-your-key-here
export OPENAI_MODEL=gpt-4o

openclaude

That is enough to start with OpenAI.

Choose Your Guide

Beginner

Want the easiest setup with copy-paste steps: Non-Technical Setup
On Windows: Windows Quick Start
On macOS or Linux: macOS / Linux Quick Start

Advanced

Want source builds, Bun, local profiles, runtime checks, or more provider choices: Advanced Setup

Common Beginner Choices

OpenAI

Best default if you already have an OpenAI API key.

Ollama

Best if you want to run models locally on your own machine.

Codex

Best if you already use the Codex CLI or ChatGPT Codex backend.

Atomic Chat

Best if you want local inference on Apple Silicon with Atomic Chat. See Advanced Setup.

VS Code Extension

Want a native VS Code experience? Use the in-repo extension at vscode-extension/openclaude-vscode for one-command terminal launch and the OpenClaude Terminal Black theme.

What Works

All tools: Bash, FileRead, FileWrite, FileEdit, Glob, Grep, WebFetch, WebSearch, Agent, MCP, LSP, NotebookEdit, Tasks
Streaming: Real-time token streaming
Tool calling: Multi-step tool chains (the model calls tools, gets results, continues)
Images: Base64 and URL images passed to vision models
Slash commands: /commit, /review, /compact, /diff, /doctor, etc.
Sub-agents: AgentTool spawns sub-agents using the same provider
Memory: Persistent memory system

What's Different

No thinking mode: Anthropic's extended thinking is disabled (OpenAI models use different reasoning)
No prompt caching: Anthropic-specific cache headers are skipped
No beta features: Anthropic-specific beta headers are ignored
Token limits: Defaults to 32K max output — some models may cap lower, which is handled gracefully

Web Search and Fetch

By default, WebSearch is disabled for all non-Anthropic providers. The native search backend requires either the Anthropic API or the Codex responses endpoint, so users on GPT-4o, DeepSeek, Gemini, Ollama, and other OpenAI-compatible providers get no web search at all.

WebFetch works but uses basic HTTP plus HTML-to-markdown conversion. That fails on JavaScript-rendered pages (React, Next.js, Vue SPAs) and sites that block plain HTTP requests.

Set a Firecrawl API key to fix both:

export FIRECRAWL_API_KEY=your-key-here

With this set:

WebSearch is enabled for all providers and routes through Firecrawl's search API
WebFetch uses Firecrawl's scrape endpoint instead of raw HTTP, handling JS-rendered pages correctly

Free tier at firecrawl.dev includes 500 credits. The key is optional — if not set, both tools fall back to their original behavior.

How It Works

The shim (src/services/api/openaiShim.ts) sits between Claude Code and the LLM API:

Claude Code Tool System
        |
        v
  Anthropic SDK interface (duck-typed)
        |
        v
  openaiShim.ts  <-- translates formats
        |
        v
  OpenAI Chat Completions API
        |
        v
  Any compatible model

It translates:

Anthropic message blocks → OpenAI messages
Anthropic tool_use/tool_result → OpenAI function calls
OpenAI SSE streaming → Anthropic stream events
Anthropic system prompt arrays → OpenAI system messages

The rest of Claude Code doesn't know it's talking to a different model.

Model Quality Notes

Not all models are equal at agentic tool use. Here's a rough guide:

Model	Tool Calling	Code Quality	Speed
GPT-4o	Excellent	Excellent	Fast
DeepSeek-V3	Great	Great	Fast
Gemini 2.0 Flash	Great	Good	Very Fast
Llama 3.3 70B	Good	Good	Medium
Mistral Large	Good	Good	Fast
GPT-4o-mini	Good	Good	Very Fast
Qwen 2.5 72B	Good	Good	Medium
Smaller models (<7B)	Limited	Limited	Very Fast

For best results, use models with strong function/tool calling support.

Files Changed from Original

src/services/api/openaiShim.ts   — NEW: OpenAI-compatible API shim (724 lines)
src/services/api/client.ts       — Routes to shim when CLAUDE_CODE_USE_OPENAI=1
src/utils/model/providers.ts     — Added 'openai' provider type
src/utils/model/configs.ts       — Added openai model mappings
src/utils/model/model.ts         — Respects OPENAI_MODEL for defaults
src/utils/auth.ts                — Recognizes OpenAI as valid 3P provider

6 files changed. 786 lines added. Zero dependencies added.

Origin

This is a fork of instructkr/claude-code, which mirrored the Claude Code source snapshot that became publicly accessible through an npm source map exposure on March 31, 2026.

The original Claude Code source is the property of Anthropic. This repository is not affiliated with or endorsed by Anthropic.

License

This repository is provided for educational and research purposes. The original source code is subject to Anthropic's terms. The OpenAI shim additions are public domain.