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 (download from nodejs.org)
• Claude Code CLI (installed automatically by setup wizard)
• Google account(s) for authentication

Installation

Windows Installation

Step 1: Install Node.js

1. Download Node.js 18+ from nodejs.org
2. Run the installer and follow the setup wizard
3. Restart your computer (or just close & reopen PowerShell)
4. Verify installation in PowerShell:

   node --version
   npm --version

Step 2: Install proxy-claude

Open PowerShell or Command Prompt and run:

npm install -g @kamel-ahmed/proxy-claude
proxy-claude init

Step 3: Complete Setup Wizard

The wizard will:

• ✅ Check Node.js and Claude Code CLI
• ✅ Add your Google account(s)
• ✅ Pick models for each tier
• ✅ Auto-configure settings

Step 4: Start Using

proxy-claude

That's it! Claude Code will launch connected to the proxy.

macOS/Linux Installation

Step 1: Install Node.js (if not already installed)

# macOS with Homebrew
brew install node

# Or download from https://nodejs.org

Step 2: Install proxy-claude

npm install -g @kamel-ahmed/proxy-claude
proxy-claude init

Step 3: Start Using

proxy-claude

Quick Install (Recommended)

# Install globally
npm install -g @kamel-ahmed/proxy-claude

# Run setup wizard
proxy-claude init

The setup wizard will:

1. ✅ Check prerequisites (Node.js, Claude Code CLI)
2. ✅ Help you add Google account(s)
3. ✅ Let you pick models for each tier (Opus, Sonnet, Haiku)
4. ✅ Auto-configure ~/.claude/settings.json

After setup, just run:

proxy-claude

This will:

1. Start the proxy server in the background
2. Wait for the server to be ready
3. Launch Claude Code CLI connected to the proxy
4. Automatically shut down the proxy when you exit

Quick Install (All Platforms)

# Install globally
npm install -g @kamel-ahmed/proxy-claude

# Run setup wizard
proxy-claude init

The setup wizard will:

1. ✅ Check prerequisites (Node.js, Claude Code CLI)
2. ✅ Help you add Google account(s)
3. ✅ Let you pick models for each tier (Opus, Sonnet, Haiku)
4. ✅ Auto-configure ~/.claude/settings.json

After setup, just run:

proxy-claude

This will:

1. Start the proxy server in the background
2. Wait for the server to be ready
3. Launch Claude Code CLI connected to the proxy
4. Automatically shut down the proxy when you exit

Troubleshooting

Windows: "npm: The term 'npm' is not recognized"

Solution: Node.js wasn't installed correctly or PowerShell needs to be restarted.

1. Download and reinstall Node.js from nodejs.org
2. Close PowerShell/Command Prompt completely
3. Reopen PowerShell as Administrator
4. Try again: npm --version

Windows: "proxy-claude: The term 'proxy-claude' is not recognized"

Solution: npm install path isn't in your PATH environment variable.

# Find where npm installed it
npm config get prefix

# Add to PATH (replace C:\Users\YourUsername\AppData\Roaming\npm if different):
$env:Path += ";C:\Users\$env:USERNAME\AppData\Roaming\npm"

Then close and reopen PowerShell.

Port Already in Use

If port 8080 is already in use, specify a different port:

PORT=3000 proxy-claude
# or
proxy-claude --port 3000

"Claude Code CLI not found" Error

The setup wizard will automatically install Claude Code CLI for you. If it fails:

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

Settings Not Persisting

The wizard auto-configures ~/.claude/settings.json. You can verify it was created:

Windows:

notepad "$env:USERPROFILE\.claude\settings.json"

macOS/Linux:

cat ~/.claude/settings.json

CLI Commands

proxy-claude              # Start proxy + Claude Code (default)
proxy-claude init         # Run setup wizard
proxy-claude start        # Start proxy server only
proxy-claude stop         # Stop proxy server  
proxy-claude status       # Check if proxy is running
proxy-claude accounts     # Manage Google accounts
proxy-claude refresh      # Refresh account tokens
proxy-claude --help       # Show all commands

Custom port:

PORT=3000 proxy-claude
proxy-claude --port 3000

Cross-Platform Support

Works on Windows, macOS, and Linux with full feature parity.

Alternative: npx (No Install)

# Run directly without installing
npx @kamel-ahmed/proxy-claude

# Or just start the server
npx @kamel-ahmed/proxy-claude start

Development: Clone Repository

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

Quick Start

If you used proxy-claude init, you're already set up! Just run:

proxy-claude

Manual Setup (Alternative)

1. Start the Proxy Server

proxy-claude 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.

Method B: CLI (Desktop or Headless)

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

# Desktop (opens browser)
proxy-claude accounts add

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

For full CLI account management options, run proxy-claude 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 proxy-claude 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"

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. Select your preferred models and click Apply to Claude CLI.

[!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": "gemini-2.5-flash-lite[1m]",
    "CLAUDE_CODE_SUBAGENT_MODEL": "claude-sonnet-4-5-thinking",
    "ENABLE_EXPERIMENTAL_MCP_CLI": "true"
  }
}

(Please use gemini-2.5-flash-lite as the default haiku model, even if others are claude, as claude code makes several calls via the haiku model for background tasks. If you use claude model for it, you may use you claude usage sooner)

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-2.5-flash-lite[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
proxy-claude 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.

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.

Available Models

Claude Models

| Model ID | Description | | ---------------------------- | ---------------------------------------- | | claude-sonnet-4-5-thinking | Claude Sonnet 4.5 with extended thinking | | claude-opus-4-5-thinking | Claude Opus 4.5 with extended thinking | | claude-sonnet-4-5 | Claude Sonnet 4.5 without thinking |

Gemini Models

| Model ID | Description | | ------------------- | ------------------------------- | | gemini-3-flash | Gemini 3 Flash with thinking | | gemini-3-pro-low | Gemini 3 Pro Low with thinking | | gemini-3-pro-high | Gemini 3 Pro High with thinking |

Gemini models include full thinking support with thoughtSignature handling for multi-turn conversations.

Multi-Account Load Balancing

When you add multiple accounts, the proxy intelligently distributes requests across them using configurable selection strategies.

Account Selection Strategies

Choose a strategy based on your needs:

| Strategy | Best For | Description | | --- | --- | --- | | Hybrid (Default) | Most users | Smart selection combining health score, token bucket rate limiting, and LRU freshness | | Sticky | Prompt caching | Stays on the same account to maximize cache hits, switches only when rate-limited | | Round-Robin | Even distribution | Cycles through accounts sequentially for balanced load |

Configure via CLI:

proxy-claude start --strategy=hybrid    # Default: smart distribution
proxy-claude start --strategy=sticky    # Cache-optimized
proxy-claude start --strategy=round-robin  # Load-balanced

Or via WebUI: Settings → Server → Account Selection Strategy

How It Works

• Health Score Tracking: Accounts earn points for successful requests and lose points for failures/rate-limits
• Token Bucket Rate Limiting: Client-side throttling with regenerating tokens (50 max, 6/minute)
• Automatic Cooldown: Rate-limited accounts recover automatically after reset time expires
• Invalid Account Detection: Accounts needing re-authentication are marked and skipped
• Prompt Caching Support: Session IDs derived from conversation enable cache hits across turns

Monitoring

Check account status, subscription tiers, and quota anytime:

# Web UI: http://localhost:8080/ (Accounts tab - shows tier badges and quota progress)
# CLI Table:
curl "http://localhost:8080/account-limits?format=table"

CLI Management Reference

If you prefer using the terminal for management:

# List all accounts
proxy-claude accounts list

# Verify account health
proxy-claude accounts verify

# Interactive CLI menu
proxy-claude accounts

Web Management Console

The proxy includes a built-in, modern web interface for real-time monitoring and configuration. Access the console at: http://localhost:8080 (default port).

Key Features

• Real-time Dashboard: Monitor request volume, active accounts, model health, and subscription tier distribution.
• Visual Model Quota: Track per-model usage and next reset times with color-coded progress indicators.
• Account Management: Add/remove Google accounts via OAuth, view subscription tiers (Free/Pro/Ultra) and quota status at a glance.
• Claude CLI Configuration: Edit your ~/.claude/settings.json directly from the browser.
• Persistent History: Tracks request volume by model family for 30 days, persisting across server restarts.
• Time Range Filtering: Analyze usage trends over 1H, 6H, 24H, 7D, or All Time periods.
• Smart Analysis: Auto-select top 5 most used models or toggle between Family/Model views.
• Live Logs: Stream server logs with level-based filtering and search.
• Advanced Tuning: Configure retries, timeouts, and debug mode on the fly.
• Bilingual Interface: Full support for English and Chinese (switch via Settings).

Advanced Configuration

While most users can use the default settings, you can tune the proxy behavior via the Settings → Server tab in the WebUI or by creating a config.json file.

Configurable Options

• API Key Authentication: Protect /v1/* API endpoints with API_KEY env var or apiKey in config.
• WebUI Password: Secure your dashboard with WEBUI_PASSWORD env var or in config.
• Custom Port: Change the default 8080 port.
• Retry Logic: Configure maxRetries, retryBaseMs, and retryMaxMs.
• Load Balancing: Adjust defaultCooldownMs and maxWaitBeforeErrorMs.
• Persistence: Enable persistTokenCache to save OAuth sessions across restarts.

Refer to config.example.json for a complete list of fields and documentation.

macOS Menu Bar App

For macOS users who prefer a native experience, there's a companion menu bar app that provides quick access to server controls without touching the terminal. Get it from: antigravity-claude-proxy-bar

Note: This is a GUI wrapper only. You still need to install and setup the proxy server first using one of the installation methods above.

Key Features

• Server Control: Start/stop the proxy server with a single click or ⌘S shortcut.
• Status Indicator: Menu bar icon shows server running state at a glance.
• WebUI Access: Open the web management console directly from the menu.
• Port Configuration: Customize the proxy server port (default: 8080).
• Auto-Start Options: Launch server on app start and launch app at login.
• Native Experience: Clean, native SwiftUI interface designed for macOS.

API Endpoints

| Endpoint | Method | Description | | ----------------- | ------ | --------------------------------------------------------------------- | | /health | GET | Health check | | /account-limits | GET | Account status and quota limits (add ?format=table for ASCII table) | | /v1/messages | POST | Anthropic Messages API | | /v1/models | GET | List available models | | /refresh-token | POST | Force token refresh |

Testing

Run the test suite (requires server running):

# Start server in one terminal
npm start

# Run tests in another terminal
npm test

Individual tests:

npm run test:signatures    # Thinking signatures
npm run test:multiturn     # Multi-turn with tools
npm run test:streaming     # Streaming SSE events
npm run test:interleaved   # Interleaved thinking
npm run test:images        # Image processing
npm run test:caching       # Prompt caching
npm run test:strategies    # Account selection strategies

Troubleshooting

"Could not extract token from Antigravity"

If using single-account mode with Antigravity:

1. Make sure Antigravity app is installed and running
2. Ensure you're logged in to Antigravity

Or add accounts via OAuth instead: proxy-claude accounts add

401 Authentication Errors

The token might have expired. Try:

curl -X POST http://localhost:8080/refresh-token

Or re-authenticate the account:

proxy-claude accounts

Rate Limiting (429)

With multiple accounts, the proxy automatically switches to the next available account. With a single account, you'll need to wait for the rate limit to reset.

Account Shows as "Invalid"

Re-authenticate the account:

proxy-claude accounts
# Choose "Re-authenticate" for the invalid account

Safety, Usage, and Risk Notices

Intended Use

• Personal / internal development only
• Respect internal quotas and data handling policies
• Not for production services or bypassing intended limits

Not Suitable For

• Production application traffic
• High-volume automated extraction
• Any use that violates Acceptable Use Policies

Warning (Assumption of Risk)

By using this software, you acknowledge and accept the following:

• Terms of Service risk: This approach may violate the Terms of Service of AI model providers (Anthropic, Google, etc.). You are solely responsible for ensuring compliance with all applicable terms and policies.

• Account risk: Providers may detect this usage pattern and take punitive action, including suspension, permanent ban, or loss of access to paid subscriptions.

• No guarantees: Providers may change APIs, authentication, or policies at any time, which can break this method without notice.

• Assumption of risk: You assume all legal, financial, and technical risks. The authors and contributors of this project bear no responsibility for any consequences arising from your use.

Use at your own risk. Proceed only if you understand and accept these risks.

Legal

• Not affiliated with Google or Anthropic. This is an independent open-source project and is not endorsed by, sponsored by, or affiliated with Google LLC or Anthropic PBC.

• "Antigravity", "Gemini", "Google Cloud", and "Google" are trademarks of Google LLC.

• "Claude" and "Anthropic" are trademarks of Anthropic PBC.

• Software is provided "as is", without warranty. You are responsible for complying with all applicable Terms of Service and Acceptable Use Policies.

Development

For Developers & Contributors

This project uses a local Tailwind CSS build system. CSS is pre-compiled and included in the repository, so you can run the project immediately after cloning.

Quick Start

git clone https://github.com/badri-s2001/antigravity-claude-proxy.git
cd antigravity-claude-proxy
npm install  # Automatically builds CSS via prepare hook
npm start    # Start server (no rebuild needed)

Frontend Development

If you need to modify styles in public/css/src/input.css:

# Option 1: Build once
npm run build:css

# Option 2: Watch for changes (auto-rebuild)
npm run watch:css

# Option 3: Watch both CSS and server (recommended)
npm run dev:full

File Structure:

• public/css/src/input.css - Source CSS with Tailwind @apply directives (edit this)
• public/css/style.css - Compiled & minified CSS (auto-generated, don't edit)
• tailwind.config.js - Tailwind configuration
• postcss.config.js - PostCSS configuration

Backend-Only Development

If you're only working on backend code and don't need frontend dev tools:

npm install --production  # Skip devDependencies (saves ~20MB)
npm start

Note: Pre-compiled CSS is committed to the repository, so you don't need to rebuild unless modifying styles.

Project Structure

See CLAUDE.md for detailed architecture documentation, including:

• Request flow and module organization
• Frontend architecture (Alpine.js + Tailwind)
• Service layer patterns (ErrorHandler.withLoading, AccountActions)
• Dashboard module documentation

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

License

MIT