Open Claude: How to Use Claude Code With Any AI Model

After Anthropic accidentally leaked Claude Code's source code via their npm registry, developers did what developers do — they forked it, stripped out the Anthropic lock-in, and made it work with any model provider. The result is Open Claude, and it gives you the full Claude Code experience with GPT-5, Gemini, Qwen, or any of the 300+ models available through OpenRouter.

We tested it, got it running, and put together this complete setup guide. Here's everything you need to know.

What is Open Claude?

Open Claude is a community-built, open-source version of Claude Code that replaces Anthropic's model backend with OpenRouter. This means you get all the agentic coding features of Claude Code — file editing, terminal commands, project understanding, multi-file refactoring — but powered by whatever model you choose.

It came out of the Claude Code source code leak, where a map file in Anthropic's npm registry exposed the full TypeScript source. Developers on GitHub immediately started building open-source replicas, and Open Claude is the most polished of those efforts.

One of the Open Claude repositories on GitHub — Screenshot by PopularAiTools.ai

Why Use Open Claude Instead of Claude Code?

Claude Code vs Open Claude — the key differences

The main reasons people are switching:

• Model freedom — You're not locked into Claude models. Use GPT-5.4 for one project, Gemini for another, a cheap model for boilerplate, and Opus for architecture
• No subscription — Pay per token via OpenRouter instead of $20-$200/month. Heavy users might spend more, light users spend far less
• No usage limits — No 5-hour session caps, no peak hour throttling. You're limited only by your OpenRouter credits
• Open source — You can inspect the code, modify it, and contribute back

The trade-off is obvious: you lose official Anthropic support, updates, and the polish of the official product. And there's the DMCA question (more on that below).

Prerequisites

Before you start, you need two things installed:

1. Node.js (LTS version) — Head to nodejs.org, find your OS, and grab the LTS download. Run the installer or use the command they provide.

2. Bun — Go to bun.sh and run the install command for your OS:

3. OpenRouter API key — Create an account at openrouter.ai, add ~$5 to your wallet, and generate an API key.

OpenRouter — the unified API that connects Open Claude to 300+ models

Step-by-Step Installation

The full installation flow at a glance

Step 1: Download the Source Code

Go to the Open Claude repository on GitHub (search for "claude-code-anymodel" or similar — repos move around due to DMCA). Download the source code as a ZIP file.

Step 2: Place It Somewhere Permanent

Unzip the source code and put it somewhere stable on your machine:

• Mac: /Applications/open-claude/
• Windows: C:\Program Files\open-claude\
• Linux: /opt/open-claude/

Don't put it on your Desktop or in Downloads — this needs to stay put.

Step 3: Build and Link

Open the folder in VS Code (or Cursor, or any IDE with a terminal), then run:

This does three things: installs dependencies, builds the project, and creates a symlink so you can run the open-claude command from any folder on your computer.

Step 4: Configure Environment Variables

Open a terminal in the project folder where you want to work (not the Open Claude installation folder — your actual project). Set these environment variables:

export OPENAI_API_KEY="your-openrouter-api-key"
export OPENAI_BASE_URL="https://openrouter.ai/api/v1"
export OPENAI_MODEL="google/gemini-3-flash-preview"

$env:OPENAI_API_KEY="your-openrouter-api-key"
$env:OPENAI_BASE_URL="https://openrouter.ai/api/v1"
$env:OPENAI_MODEL="google/gemini-3-flash-preview"

Important: These variables need to be set each time you open a new terminal session. They're not saved permanently.

Step 5: Run It

That's it. You should see the agent boot up, confirm your model provider, and be ready for prompts. It'll ask for file edit permissions on first use — select "allow for session" to avoid repeated prompts.

Configuring OpenRouter and Choosing a Model

OpenRouter's model browser — 300+ models to choose from

OpenRouter is a platform that aggregates LLM providers behind a single API. You fund your account, get an API key, and then route requests to any model. The pricing is transparent — you pay the model provider's rate plus a small OpenRouter fee.

OpenRouter's pricing — pay only for what you use

To pick a model, browse openrouter.ai/models and find one that fits your needs. Copy the model ID (e.g., google/gemini-3-flash-preview) and set it in your OPENAI_MODEL environment variable.

How to Switch Models

Switching is straightforward:

1. Exit your current Open Claude session
2. Go to OpenRouter and find the model you want
3. Copy the model ID
4. Update your OPENAI_MODEL export with the new ID
5. Re-run the export commands
6. Start Open Claude again

You can switch models per project — use a cheap model for boilerplate, a strong one for complex architecture, and a free one for formatting.

Best Models for Coding With Open Claude

The best model options for coding with Open Claude

OpenRouter's curated coding models collection

Our recommendation: start with Gemini Flash 3 Preview for most work. It's fast, cheap, and handles coding tasks well. Switch to a premium model only when you hit a task that genuinely needs it.

The DMCA Situation: What You Need to Know

Here's the elephant in the room. Anthropic is actively issuing DMCA takedown requests on GitHub repos that contain their leaked source code. Some repos have already been frozen or removed entirely.

The community is responding by:

• Distributing source code as ZIP files outside of GitHub
• Creating "clean room" implementations that rewrite functionality without copying code
• Maintaining mirrors on platforms outside US DMCA jurisdiction

The claude-code-anymodel repo takes a different approach — it's described as a proxy layer rather than a direct fork, which may give it more legal resilience. But nothing is guaranteed.

OpenRouter's API docs — useful reference for customizing your setup

Our take: If you want stability and official support, stick with Claude Code. If you want model flexibility and pay-per-token pricing, Open Claude is worth exploring — just be aware that repos may move or disappear.

Also worth watching: tools like OpenCode are building similar multi-provider agentic coding tools from scratch (not forked from leaked code), which avoids the legal gray area entirely.

The Bottom Line

Open Claude proves that the agentic coding workflow Claude Code pioneered isn't locked to one company's models. The genie is out of the bottle. Whether through Open Claude, clean-room alternatives like OpenCode, or Anthropic eventually opening up model selection themselves — the future is multi-model agentic coding.

For now, Open Claude is the fastest way to get there. Ten minutes of setup, $5 in OpenRouter credits, and you're running Claude Code with any model you want.

Frequently Asked Questions

What is Open Claude?

Open Claude is an open-source fork of Anthropic's Claude Code that allows you to use any AI model provider instead of being locked to Anthropic's models. It connects through OpenRouter, giving you access to 300+ models including GPT-5, Gemini, Qwen, GLM5, and more.

Is Open Claude free?

The Open Claude software itself is free and open source. However, you need an OpenRouter account with credits to pay for the AI model API calls. Models are pay-per-token, with some free options available. Budget around $5 to get started.

Which models work best with Open Claude?

Good affordable options include Gemini Flash 3 Preview, MiniMax M2.7, and GLM5. For higher quality, you can use GPT-5.4, Claude Sonnet, or Qwen 3.6 Plus. OpenRouter also offers free model routing for basic tasks.

Will Open Claude get taken down by Anthropic?

Anthropic has been issuing DMCA takedowns on repositories that directly mirror their leaked source code. Some Open Claude repos have already been frozen or removed. The community continues to maintain forks, but availability may vary.

What are the prerequisites to install Open Claude?

You need Node.js (LTS version) and Bun installed on your system. You also need an OpenRouter API key with funded credits. The installation works on Mac, Windows, and Linux.

How is Open Claude different from Claude Code?

Claude Code is Anthropic's official product that only works with Claude models and requires a $20-$200/month subscription. Open Claude is a community fork that works with any model via OpenRouter, uses pay-per-token pricing, and is open source.