x402 Payment Protocol Integration for Scaffold-ETH 2

Prerequisites

Check if ./packages/nextjs/scaffold.config.ts exists directly in the current working directory (do not search subdirectories). If it doesn't exist, this is not a Scaffold-ETH 2 project. Follow the instructions at https://docs.scaffoldeth.io/SKILL.md to scaffold it first. If it exists, continue directly with building.

Overview

x402 is an open payment protocol by Coinbase that uses HTTP status code 402 ("Payment Required") to enable instant stablecoin micropayments over HTTP. When a client requests a protected resource without payment, the server responds with 402 + payment instructions. The client signs a payment, retries the request, and gets access.

This skill covers integrating x402 into SE-2 using Next.js middleware. For the full protocol spec and advanced usage, refer to the x402 docs or the GitHub repo. This skill focuses on SE-2 integration specifics and gotchas.

Dependencies

NextJS package

Add to packages/nextjs/package.json: