OpusMax Local Proxy Gateway

A lightweight local proxy that lets you use OpusMax as the backend for Claude integrations in Microsoft Office (Word, Excel, PowerPoint) and any other Claude-compatible tool — without needing an official Anthropic API subscription.

How It Works

Claude Add-in (Word/Excel/PowerPoint)
    → localhost:8080  (this proxy)
    → OpusMax API     (your OpusMax account)

The proxy translates standard Claude API requests into OpusMax format with proper authentication — no code changes needed on the Office side.

Why Use This?

• No Anthropic subscription needed — Use your existing OpusMax account
• Office Claude Add-ins — Works with any add-in that supports custom API endpoints
• Stream responses — Real-time streaming for a native chat experience
• Multi-model support — Switch between Opus 4.6, Sonnet 4.5, and Haiku 4.5
• Local testing — Develop and test Claude integrations without touching production APIs

Use Case: Claude in Microsoft Office Without a Copilot License

Microsoft 365 Copilot requires a $30/user/month license. But if you have an OpusMax account (which costs a fraction of that), you can get similar AI assistance in Word, Excel, and PowerPoint using third-party Claude add-ins.

With this proxy:

1. You write a document in Word or build a spreadsheet in Excel
2. A Claude add-in sends your request to http://localhost:8080
3. The proxy forwards it to OpusMax using your account
4. You get Claude's AI capabilities directly in your Office documents

This is ideal for:

• Writers who want AI drafting and editing in Word
• Analysts who want AI-powered formulas and insights in Excel
• Presenters who want AI-generated slides in PowerPoint
• Anyone with an OpusMax account who wants Claude in Office without paying for Copilot

Install

npm install -g opusmax-proxy

That's it — no cloning, no manual config files.

Setup

On first run, the CLI will prompt you for your OpusMax credentials:

opusmax-proxy

OpusMax Base URL [https://api.opusmax.pro]:
OpusMax API Key: your-api-key-here
Local Port [8080]:

Config saved to: ~/.opusmax-proxy/config.json

Your credentials are stored locally in ~/.opusmax-proxy/config.json and never shared.

Usage

opusmax-proxy           # Start proxy (uses saved config)
opusmax-proxy -c       # Reconfigure (change API key or URL)
opusmax-proxy --port N  # Override port
opusmax-proxy -h       # Show help

Configure Your Office Add-in

Each Claude add-in for Office has settings to point to a custom API. Configure it to use:

• Gateway URL: http://localhost:8080
• Token/Key: Leave blank (auth is handled server-side)
• API Format: anthropic (for Claude Messages API)

API Endpoints

| Endpoint | Method | Description | |----------|--------|-------------| | /health | GET | Health check | | / | GET | Service info | | /v1/models | GET | List available models | | /v1/models/info | GET | Model details by tier | | /v1/messages | POST | Anthropic format (streaming supported) | | /v1/chat/completions | POST | OpenAI format (streaming supported) |

Health Check

curl http://localhost:8080/health

Stop

Ctrl+C

Requirements

• Node.js 18+
• OpusMax account with API access
• Claude add-in for Office that supports custom endpoints

Notes

• Your API key is stored locally in ~/.opusmax-proxy/config.json and never shared
• The proxy runs entirely on your machine
• Streaming must be enabled in your add-in settings for real-time responses