How to Use Claude Opus 4.5 for FREE with Clawdbot

The Problem: AI APIs Are Expensive

Let's be honest — Claude Opus 4.5 is incredible, but Anthropic's API pricing can burn through your wallet faster than a developer burns through coffee. We're talking $15 per million input tokens and $75 per million output tokens. For heavy users, that adds up to hundreds of dollars monthly.

But here's the thing: Google's Antigravity platform offers free access to Claude models (including Opus 4.5!) through their public preview. And with Clawdbot, you can harness this power through a proper AI assistant that lives in your terminal, Telegram, Discord, or wherever you want it.

What You'll Get

• Claude Opus 4.5 (with thinking/extended reasoning) — Anthropic's most powerful model
• Claude Sonnet 4.5 (fast and capable) — Great for everyday tasks
• Gemini 3 Pro/Flash (Google's latest) — Multimodal capabilities
• All accessible through Clawdbot's agentic interface with tool use
• Multi-account load balancing for higher rate limits
• Integration with Telegram, Discord, Slack, and more

Prerequisites

Before we start, make sure you have:

• Node.js 18+ installed (download here)
• A Google account (free tier works!)
• Terminal access (macOS, Linux, or WSL on Windows)

Step 1: Install Clawdbot

If you haven't already, install Clawdbot globally:

npm install -g clawdbot

Or with bun (faster):

bun install -g clawdbot

Step 2: Run the Onboarding Wizard

Clawdbot has a guided setup wizard that walks you through configuration:

clawdbot onboard

This will create your config file at ~/.clawdbot/clawdbot.json and set up the basics.

Step 3: Enable the Antigravity Auth Plugin

Here's where the magic happens. Clawdbot ships with a bundled plugin for Google Antigravity OAuth — it's just disabled by default. Enable it:

clawdbot plugins enable google-antigravity-auth

This plugin handles all the OAuth complexity for you — no need to manage tokens manually.

Step 4: Login with Google OAuth

Now authenticate with your Google account:

clawdbot models auth login --provider google-antigravity --set-default

This opens your browser for Google OAuth. Sign in, authorize access, and you're done. The plugin stores your refresh token securely and handles token refresh automatically.

Pro Tip: Multi-Account Load Balancing

Antigravity has rate limits per Google account. To maximize throughput, you can add multiple accounts:

clawdbot models auth login --provider google-antigravity

Run this again to add additional Google accounts. Clawdbot automatically rotates between them when one hits rate limits. This is especially useful for:

• Heavy development sessions
• Running multiple projects simultaneously
• Teams sharing Clawdbot instances

Step 5: Set Your Default Model

Now set Claude Opus 4.5 (with thinking) as your default model:

clawdbot models set google-antigravity/claude-opus-4-5-thinking

Other available models include:

• google-antigravity/claude-sonnet-4-5 — Fast, capable
• google-antigravity/claude-sonnet-4-5-thinking — With extended reasoning
• google-antigravity/gemini-3-pro-preview — Google's latest
• google-antigravity/gemini-3-flash — Fast and efficient

Step 6: Verify Everything Works

Check your model status:

clawdbot models status

You should see your Antigravity auth profile listed with a valid token. Run doctor to verify the full setup:

clawdbot doctor

Step 7: Start the Gateway

Clawdbot runs as a background daemon. Start it:

clawdbot gateway start

Now you can interact with your AI through:

• Web UI: clawdbot dashboard
• Terminal: clawdbot tui
• Telegram/Discord: Configure channels in clawdbot configure

Complete Config Example

Here's what your ~/.clawdbot/clawdbot.json might look like after setup:

{
  "agents": {
    "defaults": {
      "model": {
        "primary": "google-antigravity/claude-opus-4-5-thinking",
        "fallbacks": ["google-antigravity/claude-sonnet-4-5"]
      },
      "workspace": "/Users/yourname/clawd"
    }
  },
  "plugins": {
    "entries": {
      "google-antigravity-auth": {
        "enabled": true
      }
    }
  },
  "gateway": {
    "port": 18789,
    "mode": "local"
  }
}

How It Works Under the Hood

Google Antigravity is Google's agentic development platform that provides access to both Gemini and Claude models through a unified API. During their public preview (which has been running since late 2025), individuals get free access with generous rate limits.

The google-antigravity-auth plugin in Clawdbot:

1. Handles OAuth 2.0 authentication with Google
2. Stores refresh tokens securely in auth profiles
3. Automatically refreshes access tokens before they expire
4. Routes requests through Antigravity's API
5. Translates between Claude's native format and Antigravity's wrapper

Rate Limits & Fair Use

Antigravity's free tier has rate limits (they change, so check their docs). If you have a Google One subscription, you get higher limits. Students with free Google One access through their university also benefit from increased quotas.

The multi-account feature helps you work around rate limits by automatically switching accounts when one is exhausted.

Troubleshooting

"No credentials found"

Re-run the login command:

clawdbot models auth login --provider google-antigravity --set-default

"Token expired"

The plugin should auto-refresh, but if not:

clawdbot models auth login --provider google-antigravity

"Rate limited"

Add more Google accounts or wait for your quota to reset (usually daily).

What's Next?

Now you have a fully functional AI assistant powered by Claude Opus 4.5 — for free. Use it for:

• Code reviews and refactoring
• Writing and editing
• Research and analysis
• Automation through Clawdbot's agentic tools
• Connecting to Telegram, Discord, Slack, and more

TL;DR - Quick Setup

# Install Clawdbot
npm install -g clawdbot

# Run onboarding
clawdbot onboard

# Enable Antigravity plugin
clawdbot plugins enable google-antigravity-auth

# Login with Google
clawdbot models auth login --provider google-antigravity --set-default

# Set Claude Opus as default
clawdbot models set google-antigravity/claude-opus-4-5-thinking

# Start the gateway
clawdbot gateway start

# Open the dashboard
clawdbot dashboard

That's it. You're now running one of the most powerful AI models in the world, completely free. Go build something amazing. 🚀