Antigravity Claude Proxy

A proxy server that exposes an Anthropic-compatible API backed by Antigravity's Cloud Code, letting you use Claude and Gemini models with Claude Code CLI.

How It Works

┌──────────────────┐     ┌─────────────────────┐     ┌────────────────────────────┐
│   Claude Code    │────▶│  This Proxy Server  │────▶│  Antigravity Cloud Code    │
│   (Anthropic     │     │  (Anthropic → Google│     │  (daily-cloudcode-pa.      │
│    API format)   │     │   Generative AI)    │     │   sandbox.googleapis.com)  │
└──────────────────┘     └─────────────────────┘     └────────────────────────────┘

1. Receives requests in Anthropic Messages API format
2. Uses OAuth tokens from added Google accounts (or Antigravity's local database)
3. Transforms to Google Generative AI format with Cloud Code wrapping
4. Sends to Antigravity's Cloud Code API
5. Converts responses back to Anthropic format with full thinking/streaming support

Prerequisites

• Node.js 18 or later
• Antigravity installed (for single-account mode) OR Google account(s) for multi-account mode

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Installation

Option 1: npm (Recommended)

# Run directly with npx (no install needed)
npx antigravity-claude-proxy@latest start

# Or install globally
npm install -g antigravity-claude-proxy@latest
antigravity-claude-proxy start

Option 2: Clone Repository

git clone https://github.com/badri-s2001/antigravity-claude-proxy.git
cd antigravity-claude-proxy
npm install
npm start

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Quick Start

1. Start the Proxy Server

# If installed via npm
antigravity-claude-proxy start

# If using npx
npx antigravity-claude-proxy@latest start

# If cloned locally
npm start

The server runs on http://localhost:8080 by default.

2. Link Account(s)

Choose one of the following methods to authorize the proxy:

Method A: Web Dashboard (Recommended)

1. With the proxy running, open http://localhost:8080 in your browser.
2. Navigate to the Accounts tab and click Add Account.
3. Complete the Google OAuth authorization in the popup window.

Headless/Remote Servers: If running on a server without a browser, the WebUI supports a "Manual Authorization" mode. After clicking "Add Account", you can copy the OAuth URL, complete authorization on your local machine, and paste the authorization code back.

Method B: CLI (Desktop or Headless)

If you prefer the terminal or are on a remote server:

# Desktop (opens browser)
antigravity-claude-proxy accounts add

# Headless (Docker/SSH)
antigravity-claude-proxy accounts add --no-browser

For full CLI account management options, run antigravity-claude-proxy accounts --help.

Method C: Automatic (Antigravity Users)

If you have the Antigravity app installed and logged in, the proxy will automatically detect your local session. No additional setup is required.

To use a custom port:

PORT=3001 antigravity-claude-proxy start

3. Verify It's Working

# Health check
curl http://localhost:8080/health

# Check account status and quota limits
curl "http://localhost:8080/account-limits?format=table"

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Using with Claude Code CLI

Configure Claude Code

You can configure these settings in two ways:

Via Web Console (Recommended)

1. Open the WebUI at http://localhost:8080.
2. Go to Settings → Claude CLI.
3. Use the Connection Mode toggle to switch between:
   • Proxy Mode: Uses the local proxy server (Antigravity Cloud Code). Configure models, base URL, and presets here.
   • Paid Mode: Uses the official Anthropic Credits directly (requires your own subscription). This hides proxy settings to prevent accidental misconfiguration.
4. Click Apply to Claude CLI to save your changes.

[!TIP] > Configuration Precedence: System environment variables (set in shell profile like .zshrc) take precedence over the settings.json file. If you use the Web Console to manage settings, ensure you haven't manually exported conflicting variables in your terminal.

Manual Configuration

Create or edit the Claude Code settings file:

macOS: ~/.claude/settings.json Linux: ~/.claude/settings.json Windows: %USERPROFILE%\.claude\settings.json

Add this configuration:

{
  "env": {
    "ANTHROPIC_AUTH_TOKEN": "test",
    "ANTHROPIC_BASE_URL": "http://localhost:8080",
    "ANTHROPIC_MODEL": "claude-opus-4-5-thinking",
    "ANTHROPIC_DEFAULT_OPUS_MODEL": "claude-opus-4-5-thinking",
    "ANTHROPIC_DEFAULT_SONNET_MODEL": "claude-sonnet-4-5-thinking",
    "ANTHROPIC_DEFAULT_HAIKU_MODEL": "claude-sonnet-4-5",
    "CLAUDE_CODE_SUBAGENT_MODEL": "claude-sonnet-4-5-thinking",
    "ENABLE_EXPERIMENTAL_MCP_CLI": "true"
  }
}

Or to use Gemini models:

{
  "env": {
    "ANTHROPIC_AUTH_TOKEN": "test",
    "ANTHROPIC_BASE_URL": "http://localhost:8080",
    "ANTHROPIC_MODEL": "gemini-3-pro-high[1m]",
    "ANTHROPIC_DEFAULT_OPUS_MODEL": "gemini-3-pro-high[1m]",
    "ANTHROPIC_DEFAULT_SONNET_MODEL": "gemini-3-flash[1m]",
    "ANTHROPIC_DEFAULT_HAIKU_MODEL": "gemini-3-flash[1m]",
    "CLAUDE_CODE_SUBAGENT_MODEL": "gemini-3-flash[1m]",
    "ENABLE_EXPERIMENTAL_MCP_CLI": "true"
  }
}

Load Environment Variables

Add the proxy settings to your shell profile:

macOS / Linux:

echo 'export ANTHROPIC_BASE_URL="http://localhost:8080"' >> ~/.zshrc
echo 'export ANTHROPIC_AUTH_TOKEN="test"' >> ~/.zshrc
source ~/.zshrc

For Bash users, replace ~/.zshrc with ~/.bashrc

Windows (PowerShell):

Add-Content $PROFILE "`n`$env:ANTHROPIC_BASE_URL = 'http://localhost:8080'"
Add-Content $PROFILE "`$env:ANTHROPIC_AUTH_TOKEN = 'test'"
. $PROFILE

Windows (Command Prompt):

setx ANTHROPIC_BASE_URL "http://localhost:8080"
setx ANTHROPIC_AUTH_TOKEN "test"

Restart your terminal for changes to take effect.

Run Claude Code

# Make sure the proxy is running first
antigravity-claude-proxy start

# In another terminal, run Claude Code
claude

Note: If Claude Code asks you to select a login method, add "hasCompletedOnboarding": true to ~/.claude.json (macOS/Linux) or %USERPROFILE%\.claude.json (Windows), then restart your terminal and try again.

Proxy Mode vs. Paid Mode

Toggle in Settings → Claude CLI:

Feature	🔌 Proxy Mode	💳 Paid Mode
Backend	Local Server (Antigravity)	Official Anthropic Credits
Cost	Free (Google Cloud)	Paid (Anthropic Credits)
Models	Claude + Gemini	Claude Only

Paid Mode automatically clears proxy settings so you can use your official Anthropic account directly.

Multiple Claude Code Instances (Optional)

To run both the official Claude Code and Antigravity version simultaneously, add this alias:

macOS / Linux:

# Add to ~/.zshrc or ~/.bashrc
alias claude-antigravity='CLAUDE_CONFIG_DIR=~/.claude-account-antigravity ANTHROPIC_BASE_URL="http://localhost:8080" ANTHROPIC_AUTH_TOKEN="test" command claude'

Windows (PowerShell):

# Add to $PROFILE
function claude-antigravity {
    $env:CLAUDE_CONFIG_DIR = "$env:USERPROFILE\.claude-account-antigravity"
    $env:ANTHROPIC_BASE_URL = "http://localhost:8080"
    $env:ANTHROPIC_AUTH_TOKEN = "test"
    claude
}

Then run claude for official API or claude-antigravity for this proxy.

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Documentation

• Available Models
• Multi-Account Load Balancing
• Web Management Console
• Advanced Configuration
• macOS Menu Bar App
• API Endpoints
• Testing
• Troubleshooting
• Safety, Usage, and Risk Notices
• Legal
• Development

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Credits

This project is based on insights and code from:

• opencode-antigravity-auth - Antigravity OAuth plugin for OpenCode
• claude-code-proxy - Anthropic API proxy using LiteLLM

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License

MIT

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