Claude Code with Gemini: A Setup Guide

Claude Code is Anthropic's CLI coding assistant—a powerful tool for developers. But what if you want to use it with Google's Gemini models instead of Anthropic's API?

This guide shows you how to set up Claude Code with Gemini using Claude Code Router, an open-source tool that redirects API requests to alternative LLM providers.

Prerequisites

Before starting, ensure you have:

• Node.js 18+ (verify with node --version)
• npm (comes with Node.js)
• Gemini API Key from Google AI Studio

Step 1: Install Claude Code

Install Claude Code globally via npm:

npm install -g @anthropic-ai/claude-code

Verify the installation:

claude --version

Step 2: Install Claude Code Router

Claude Code Router intercepts Claude Code requests and routes them to alternative LLM providers (Gemini, OpenRouter, Ollama, etc.):

npm install -g @musistudio/claude-code-router

Verify:

ccr -v

Step 3: Create Configuration File

Create the config directory and configuration file:

mkdir -p ~/.claude-code-router

Create the config file at ~/.claude-code-router/config.json:

{
  "LOG": true,
  "Providers": [
    {
      "name": "gemini",
      "api_base_url": "https://generativelanguage.googleapis.com/v1beta/models/",
      "api_key": "YOUR_GEMINI_API_KEY_HERE",
      "models": [
        "gemini-2.0-flash",
        "gemini-2.5-flash",
        "gemini-2.5-pro"
      ],
      "transformer": {
        "use": ["gemini"]
      }
    }
  ],
  "Router": {
    "default": "gemini,gemini-2.0-flash",
    "background": "gemini,gemini-2.0-flash",
    "think": "gemini,gemini-2.0-flash",
    "longContext": "gemini,gemini-2.0-flash"
  }
}

Replace YOUR_GEMINI_API_KEY_HERE with your actual Gemini API key.

Step 4: Configure Shell Environment

Add the router activation to your shell profile:

For Zsh (~/.zshrc):

echo '# Claude Code Router' >> ~/.zshrc
echo 'eval "$(ccr activate)"' >> ~/.zshrc
source ~/.zshrc

For Bash (~/.bashrc):

echo '# Claude Code Router' >> ~/.bashrc
echo 'eval "$(ccr activate)"' >> ~/.bashrc
source ~/.bashrc

This sets the following environment variables:

• ANTHROPIC_AUTH_TOKEN: A dummy token for the router
• ANTHROPIC_BASE_URL: Routes requests to local proxy at port 3456
• DISABLE_TELEMETRY: Disables telemetry

Step 5: Start the Router

Start the Claude Code Router server:

ccr start

Verify it's running:

ccr status

You should see output indicating the status is "Running" with the API endpoint at port 3456.

Step 6: Run Claude Code

Launch Claude Code with Gemini:

ccr code

When prompted about the custom API key, select "Yes" to use the router's dummy key.

Gemini Free Tier Limits

Here are the rate limits for Gemini's free tier:

gemini-2.0-flash: 1500 requests per day, 15 per minute (recommended for highest limits)

gemini-2.5-flash: 500 requests per day, 10 per minute

gemini-2.5-pro: 25 requests per day, 2 per minute

Recommendation: Use gemini-2.0-flash as default for the highest free tier limits.

Useful Commands

Here are the key commands you'll use:

• ccr start — Start the router server
• ccr stop — Stop the router server
• ccr restart — Restart the router
• ccr status — Check server status
• ccr code — Launch Claude Code with router
• ccr model — Interactive model selection
• /model gemini,gemini-2.5-pro — Switch models within Claude Code

Troubleshooting

"Rate limit exceeded" (429 error)

• Switch to a model with higher limits (e.g., gemini-2.0-flash)
• Wait for rate limit to reset (usually a few minutes)
• Generate a new API key from Google AI Studio

Claude Code shows login screen

1. Ensure router is running: ccr status
2. Ensure environment is set: eval "$(ccr activate)"
3. Restart terminal and try again

Router not starting

Check if port 3456 is already in use:

lsof -i :3456

Kill any existing process and restart:

ccr stop
ccr start

Using Multiple Providers

You can configure multiple providers for fallback or specific use cases. For example, you can use Gemini for default tasks and Ollama for background tasks by adding both to your Providers array and configuring the Router section accordingly.

Router Scenarios

The router supports different scenarios:

• default: General coding tasks
• background: Background/automated tasks
• think: Reasoning-heavy tasks (Plan Mode)
• longContext: Large file/context handling

Resources

• Claude Code Documentation: docs.claude.com
• Claude Code Router GitHub: github.com/musistudio/claude-code-router
• Google AI Studio for API Keys: aistudio.google.com
• Gemini API Rate Limits: ai.google.dev/gemini-api/docs/rate-limits