x402-middleware

X402 Merit payment middleware factory for Express, Hono, and Next.js applications. Automatically resolves repository addresses from GitHub and deploys repo contracts if needed.

Installation

npm install x402-middleware
# or
pnpm add x402-middleware

You'll also need the x402 middleware for your framework:

• Express: npm install x402-express
• Hono: npm install x402-hono
• Next.js: npm install x402-next

Usage

With Hono

import { meritPaymentMiddleware } from 'x402-middleware';
import { paymentMiddleware } from 'x402-hono';
import { Hono } from 'hono';
import type { Config } from 'x402-middleware/types';
import type { Address } from 'viem';

const app = new Hono();

const config: Config = {
    repoIdentifier: "github:owner/repo",
    repoFactoryAddress: "0x..." as Address,
    rpcUrl: "https://..." as RpcUrl,
    privateKey: "0x..." as PrivateKey,
};

app.use(meritPaymentMiddleware(
    config,
    paymentMiddleware,
    {
        "/": {
            price: "$0.01",
            network: "base",
            config: {
                description: "Pay for this repo",
            }
        }
    }
));

With Express

import { meritPaymentMiddleware } from 'x402-middleware';
import { paymentMiddleware } from 'x402-express';
import express from 'express';

const app = express();

app.use(meritPaymentMiddleware(
    config,
    paymentMiddleware,
    routes
));

API

meritPaymentMiddleware(config, paymentMiddlewareFactory, routes, facilitator?, paywall?)

Creates a repo-aware payment middleware that automatically:

1. Resolves the repository ID from GitHub
2. Gets or deploys the repo contract
3. Wraps the payment middleware with the repo address

Parameters:

• config: Configuration object
  • repoIdentifier: Repository identifier in format github:owner/repo or github:owner/repo:instanceId
  • repoFactoryAddress: Smart contract address for the repo factory
  • rpcUrl: RPC endpoint URL
  • privateKey: Private key for deploying contracts
• paymentMiddlewareFactory: Framework-specific payment middleware function (paymentMiddleware from x402-express, x402-hono, or x402-next)
• routes: Route configuration object with pricing
• facilitator?: Optional facilitator configuration
• paywall?: Optional paywall configuration

Returns: Async middleware function compatible with your framework

How it Works

1. On first request, resolves your GitHub repo to get its repo ID
2. Checks if a repo contract is deployed for that ID
3. If not deployed, automatically deploys it
4. Passes the repo address to the payment middleware
5. All payments go to the repo's smart contract address