X402 Payment Protocol with Sperax USDs

Revolutionary AI Agent Payment Infrastructure — HTTP 402 payments with yield-bearing USDs stablecoin on Arbitrum

🌟 Overview

X402 is a complete payment protocol implementation for AI agents, combining:

• HTTP 402 - Payment Required standard for programmatic payments
• Sperax USDs - Auto-yield stablecoin (8-25% APY) on Arbitrum
• EIP-3009 - Gasless transfer authorization
• Arbitrum L2 - Low-cost, fast transactions

💡 Why X402 + USDs?

Feature	Traditional Payments	X402 + USDs
Fees	2-3% + fixed	~$0.001 gas
Settlement	Days	Seconds
Yield	0%	8-25% APY
AI Native	❌	✅
Gasless	❌	✅ (EIP-3009)
Micropayments	❌	✅

📦 Packages

Package	Description
@x402/sdk	Core SDK for X402 payments
@x402/cli	Command-line interface
@x402/sperax-mcp	MCP tools for AI agents
facilitator	Payment verification server
yield-tracker	USDs yield monitoring
contracts	Solidity smart contracts

🚀 Quick Start

# Clone the repo
git clone https://github.com/nirholas/x402.git
cd x402

# Install dependencies
pnpm install

# Copy environment config
cp .env.example .env

# Start the facilitator server
pnpm facilitator:dev

# In another terminal, start yield tracker
pnpm yield-tracker

💰 Make a Payment

Using the SDK

import { X402Client } from '@x402/sdk';

const client = new X402Client({
  network: 'arbitrum',
  facilitatorUrl: 'http://localhost:3002'
});

// Gasless payment with EIP-3009
const { txHash } = await client.pay({
  recipient: '0x...',
  amount: '1.50',  // $1.50 USDs
  token: 'USDs',
  gasless: true
});

console.log('Payment confirmed:', txHash);

Using MCP Tools (AI Agents)

{
  "tool": "x402_pay_with_usds",
  "arguments": {
    "recipient": "0x...",
    "amount": "1.50",
    "gasless": true,
    "memo": "API call payment"
  }
}

📈 Earn Yield on Payments Received

USDs automatically earns yield while sitting in your wallet:

import { SperaxClient } from '@x402/sdk';

const client = new SperaxClient({ network: 'arbitrum' });

// Check balance with yield earned
const { balance, yieldEarned, apy } = await client.getBalanceWithYield(address);

console.log(`Balance: $${balance}`);
console.log(`Yield Earned: $${yieldEarned}`);
console.log(`Current APY: ${apy}%`);

🔧 Architecture

┌─────────────┐     HTTP 402      ┌─────────────────┐
│   AI Agent  │ ◄─────────────────│   API Server    │
│   (Payer)   │                   │   (Paywall)     │
└──────┬──────┘                   └────────┬────────┘
       │                                   │
       │ EIP-3009 Auth                     │ Verify
       ▼                                   ▼
┌─────────────────────────────────────────────────────┐
│                 Facilitator Server                   │
│  • Verify payment authorizations                     │
│  • Submit transactions                               │
│  • Track yields                                      │
└──────────────────────┬──────────────────────────────┘
                       │
                       ▼
         ┌─────────────────────────┐
         │   Arbitrum Network      │
         │  ┌───────────────────┐  │
         │  │   USDs Token      │  │
         │  │   (Auto-Yield)    │  │
         │  └───────────────────┘  │
         └─────────────────────────┘

🎯 Use Cases

1. AI Agent Tool Marketplace

Pay per API call with micropayments. No subscriptions, no minimums.

2. Content Monetization

Paywall articles, videos, or data with instant USDs payments.

3. Revenue Splitting

Automatic 80/20 split between developers and platforms.

4. Subscription Streaming

Pay-as-you-go subscriptions that auto-renew with yield earnings.

📋 Contract Addresses

Arbitrum Mainnet

Contract	Address
USDs Token	0xD74f5255D557944cf7Dd0E45FF521520002D5748
Sperax Vault	0x8EC1877698ACF262Fe8Ad8a295ad94D6ea258988
Revenue Splitter	Deploy your own

Arbitrum Sepolia (Testnet)

Contract	Address
USDs Token	See deployment docs

🛠️ Development

# Run all tests
pnpm test

# Run contract tests
pnpm contracts:test

# Build all packages
pnpm build

# Format code
pnpm format

# Lint
pnpm lint

📚 Documentation

• Getting Started Guide
• API Reference
• Smart Contracts
• MCP Integration
• Sperax USDs Docs

🤝 Contributing

Contributions are welcome! Please read our Contributing Guide first.

📄 License

MIT License - see LICENSE for details.

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Built with ❤️ for the AI economy

X402 is not affiliated with Sperax or Coinbase. USDs is a product of Sperax Foundation.