How to Hook Google Antigravity into Claude Code for Free Opus 4.5 Access

Antigravity-Manager is an open‑source account‑management and API reverse‑proxy tool that bridges Claude Code’s user‑friendly front‑end with Google’s generous Antigravity free quota.

The motivation is simple: Claude Code offers a smooth UI, but Claude 4.5/Opus models are costly, whereas Google Antigravity provides high‑quality models with abundant free credits. The tool connects the two, letting users keep the Claude experience while routing backend calls to Google.

1. Token Saver (smart routing) – The tool deep‑inspects request payloads and identifies non‑essential “garbage” requests such as title generation, concise summaries, and next‑prompt suggestions. These are silently broken off and sent to the fast, free Gemini 2.5 Flash model, preserving expensive Opus/Sonnet quota for core programming logic.

2. Session Sticky – To avoid context drift, Antigravity-Manager locks a conversation to the same Google account for a 60‑second sliding window, ensuring that the model remembers prior interactions, a feature that can be more critical than the official API for Claude Code’s long‑context agents.

3. Google Becomes Claude – The latest version maps Claude model identifiers (e.g., claude-3-7-sonnet or opus-4-5) to Google Antigravity’s protocol, effectively translating Claude requests into Google‑compatible calls and invoking top‑tier Google models or their mirrored equivalents.

Getting Started

Project is built with Rust (Tauri v2) + React, offering strong performance and cross‑platform support.

Step 1: Install – Download the appropriate installer from the GitHub Releases page. macOS users can run brew install --cask antigravity-manager; Windows users download the .msi or .exe package.

Step 2: Import Accounts – Launch the app and import Google Antigravity token(s). The tool supports batch import and automatic load‑balancing across multiple accounts.

Step 3: Configure Claude Code – Point Claude Code to the local proxy by setting the environment variable, for example:

# Set proxy address (note the /v1 suffix)
export ANTHROPIC_BASE_URL="http://127.0.0.1:11434/v1"

# Start Claude Code
claude

After configuration, Claude Code operates as usual, but all backend consumption is handled by Google’s free quota, dramatically reducing costs.