solana-x402-facilitator

The first x402 payment facilitator for Solana.

x402 is the HTTP 402 Payment Required standard for machine-to-machine micropayments (Linux Foundation). Until now, it only worked on EVM chains (Base, Ethereum). This package brings x402 to Solana.

Why Solana?

| | EVM (Base) | Solana | |---|---|---| | Finality | ~2 seconds | ~400ms | | Transaction fee | ~$0.01 | ~$0.00025 | | Micropayment viable | $0.01+ | $0.001+ | | AI agent ecosystem | Growing | Massive |

Install

npm install solana-x402-facilitator

Quick Start

const express = require("express");
const { createMiddleware } = require("solana-x402-facilitator");

const app = express();

app.use(createMiddleware({
  rpcUrl: "https://mainnet.helius-rpc.com/?api-key=YOUR_KEY",
  payTo: "YOUR_SOLANA_ADDRESS",
  routes: {
    "GET /api/data": { price: "$0.01", description: "Premium data endpoint" }
  }
}));

app.get("/api/data", (req, res) => {
  // req.x402 contains payment info (payer, amount, signature)
  res.json({ data: "premium content", paidBy: req.x402.payer });
});

app.listen(3000);

How It Works

1. Client requests a paid endpoint
2. Server returns HTTP 402 with Solana payment requirements
3. Client builds & signs SPL USDC transfer transaction
4. Client sends request with x-payment header
5. Facilitator verifies signature, amount, and destination
6. Facilitator settles transaction on Solana (~400ms)
7. Server returns the response

API

createMiddleware(config)

Express middleware for x402 payments.

verifyPayment(paymentHeader, requirements, connection)

Low-level payment verification.

settlePayment(tx, connection, opts)

Low-level on-chain settlement.

License

MIT — Built by Tom Smart (@tomsmart_ai)