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

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

Quick Start

1. Start the Proxy Server

# If installed globally
acc start
# or: antigravity-claude-proxy start

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

# If cloned locally
npm start

The server launches as a background process on http://localhost:8080 by default and survives terminal closure.

| Command | Description | | :--- | :--- | | acc start | Launch proxy in the background | | acc stop | Shut down the proxy | | acc restart | Restart the proxy | | acc status | Check proxy health and PID | | acc ui | Open the web dashboard | | acc start --log | Run in foreground with visible logs |

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"

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-4-6-thinking",
    "ANTHROPIC_DEFAULT_OPUS_MODEL": "claude-opus-4-6-thinking",
    "ANTHROPIC_DEFAULT_SONNET_MODEL": "claude-sonnet-4-6-thinking",
    "ANTHROPIC_DEFAULT_HAIKU_MODEL": "claude-sonnet-4-6",
    "CLAUDE_CODE_SUBAGENT_MODEL": "claude-sonnet-4-6-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-3.1-pro-high[1m]",
    "ANTHROPIC_DEFAULT_OPUS_MODEL": "gemini-3.1-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.

Running as a System Service (systemd)

When running as a systemd service, the proxy runs under a different user (e.g. root), so it can't find your Claude CLI settings at ~/.claude/settings.json. Set CLAUDE_CONFIG_PATH to point to the real user's .claude directory:

# /etc/systemd/system/antigravity-proxy.service
[Service]
Environment=CLAUDE_CONFIG_PATH=/home/youruser/.claude
ExecStart=/usr/bin/node /path/to/antigravity-claude-proxy/src/index.js

Without this, the WebUI's Claude CLI tab won't be able to read or write your Claude Code configuration.

Documentation

• Available Models
• Multi-Account Load Balancing
• Web Management Console
• Advanced Configuration
• [macOS Menu Bar App](docs/menu