x402 Chat Completions API on Vercel

This is an Express.js application that provides OpenAI-compatible chat completions using Hyperbolic AI, with x402 payment processing integration.

Features

• OpenAI-compatible /v1/chat/completions endpoint
• Hyperbolic AI integration for LLM inference
• x402 payment processing (Base Sepolia network)
• Comprehensive logging with Winston
• Request validation with Zod
• Security middleware with Helmet
• Health and readiness checks
• Graceful shutdown handling

API Endpoints

Chat Completions

• POST /v1/chat/completions - OpenAI-compatible chat completions endpoint
  • Requires payment via x402 ($0.001 per request)
  • Supports standard OpenAI parameters: model, messages, max_tokens, temperature, top_p, stream

Health Checks

• GET /health - Basic health check
• GET /ready - Readiness check (validates external dependencies)

Setup

1. Install dependencies:

pnpm install

2. Create a .env file with the required environment variables:

# Hyperbolic AI API Key
HYPERBOLIC_API_KEY=your_hyperbolic_api_key_here

# Payment Configuration
ADDRESS=0x1234567890123456789012345678901234567890
FACILITATOR_URL=https://your-facilitator-url.com

# For testing with the client
PRIVATE_KEY=0x1234567890123456789012345678901234567890123456789012345678901234

# Optional Configuration
ALLOWED_ORIGINS=http://localhost:3000,https://yourdomain.com
LOG_LEVEL=info
NODE_ENV=development
PORT=3000

3. Start the development server:

pnpm run dev

Testing with the Client

A test client is included to demonstrate x402 payment functionality:

pnpm run client

The client will:

1. Create an account from your private key
2. Make a chat completion request with payment
3. Display the AI response and payment details

Usage Example

curl -X POST https://your-vercel-app.vercel.app/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "meta-llama/Llama-3.2-3B-Instruct",
    "messages": [
      {"role": "user", "content": "Hello, how are you?"}
    ],
    "max_tokens": 100
  }'

Deployment

One-Click Deploy

Deploy to Vercel:

Manual Deploy

pnpm run deploy

Environment Variables for Production

Make sure to set these in your Vercel dashboard:

• HYPERBOLIC_API_KEY
• ADDRESS
• FACILITATOR_URL
• ALLOWED_ORIGINS (optional)
• LOG_LEVEL (optional)