Developer Configuration Layer

Overview

To make 402Gate developer-friendly, it includes a configuration SDK and endpoint templates that make any HTTP service instantly monetizable.

Features

• Simple middleware for Node.js / Next.js / Express.

• Built-in helpers to attach pricing logic per endpoint.

• Automatic generation of 402 responses and verification flow.

• TypeScript support for strict typing.

Example Implementation

import { create402Middleware } from "@402gate/sdk";

app.use("/api/premium", create402Middleware({
  price: 0.001,
  token: "402G",
  recipient: "MERCHANT_PUBKEY",
  verifyOnChain: true
}));

SDK Components

• create402Middleware() — wrap protected endpoints.

• verifyPayment() — validate tx proof.

• fetchWith402() — client-side auto-retry for 402 responses.

Developer Experience

With the SDK, any developer can turn their REST API into a Web3-native pay-per-use service in minutes without building a smart contract or handling complex crypto logic.