nexuspay-x402

NexusPay for x402 - add payments to any API in 3 lines.

Install

npm install nexuspay-x402

Express Usage

import nexuspay from 'nexuspay-x402';

app.use(nexuspay({
  apiKey: 'np_your_key',
  price: '0.001',
  payTo: '0xYourWallet'
}));

Next.js Usage

import { nexuspayNext } from 'nexuspay-x402';

export async function GET(request: Request) {
  const check = await nexuspayNext(request, {
    apiKey: 'np_your_key',
    price: '0.001',
    payTo: '0xYourWallet'
  });
  
  if (check) return check;
  
  // Your API logic here
  return Response.json({ data: 'Protected content' });
}

How it works

1. Request comes in
2. No payment? → 402 returned automatically
3. Payment header found? → Verified on Base Sepolia
4. Verified? → API access granted

Built on Base Sepolia. Payments in USDC.

Features

• ✅ 3-line integration
• ✅ On-chain payment verification
• ✅ ERC-20 Transfer event decoding
• ✅ Works with Express and Next.js
• ✅ AI agent compatible
• ✅ TypeScript support

Configuration

interface NexusPayConfig {
  apiKey?: string;     // Optional API key for app-side tracking
  price: string;       // Price in USDC (e.g., '0.001')
  payTo: string;       // Your wallet address
  token?: string;      // Token address (default: USDC)
  network?: string;    // Network (default: 'base-sepolia')
  enabled?: boolean;   // Set false to bypass checks in local dev
  rpcUrl?: string;     // Optional custom RPC URL
}

Payment Header Format

Clients must include payment proof in the X-Payment header:

X-Payment: txHash=0x...;from=0x...;to=0x...;amount=0.001;token=0x...;network=base-sepolia

Example: Protected API

import express from 'express';
import nexuspay from 'nexuspay-x402';

const app = express();

// Protect this route
app.get('/api/data', 
  nexuspay({
    apiKey: 'np_your_key',
    price: '0.001',
    payTo: '0xA1B320D8061357efa286Af2629DF6AC554C05d6E'
  }),
  (req, res) => {
    res.json({ data: 'This is protected content!' });
  }
);

app.listen(3000);

Example: AI Agent Client

// 1. Call API
const response = await fetch('https://api.example.com/data');

// 2. Got 402? Pay with USDC
if (response.status === 402) {
  const { payment } = await response.json();
  
  // Send USDC on Base Sepolia
  const txHash = await sendUSDC(payment.payTo, payment.amount);
  
  // 3. Retry with payment proof
  const response2 = await fetch('https://api.example.com/data', {
    headers: {
      'X-Payment': `txHash=${txHash};from=${myAddress};to=${payment.payTo};amount=${payment.amount};token=${payment.token};network=base-sepolia`
    }
  });
  
  const data = await response2.json();
}

Network Details

• Network: Base Sepolia (testnet)
• Chain ID: 84532
• USDC Contract: 0x036CbD53842c5426634e7929541eC2318f3dCF7e
• RPC: https://sepolia.base.org

Get Test USDC

Visit: https://www.coinbase.com/faucets/base-ethereum-sepolia-faucet

License

MIT

Backward Compatibility

nexuspay-x402 also exports paygate and paygateNext aliases so older integrations can migrate gradually.

Links

• x402 Protocol: https://github.com/coinbase/x402
• NexusPay Docs: https://github.com/dhruvxop19/nexuspay

Built with the x402 protocol by Coinbase.