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Quick summary

Gx402 provides x402 integration examples and server middleware so teams can accept in-app payments (miniapps) and in-game purchases from engine builds (Unity/Unreal) running inside Farcaster or as standalone games. We are not shipping a proprietary SDK — instead, you get:
  • Engine-native examples
  • A recommended Express middleware pattern
  • Deployment notes for reliable x402 payments (create → sign → confirm → finalize)
(Adapted from the x402 miniapp template)

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Prerequisites

  • Node.js 18+ and a package manager (pnpm, npm, or yarn)
  • Farcaster uses it’s In-App wallet connection so you don’t need any external wallet to connect
  • x402 provider account & API keys (from your x402 provider)
  • Unity (2021+) or Unreal (4.27+/5.x) for engine builds intended to run inside Farcaster or as standalone apps
  • Basic knowledge of wallet signing (EIP-191 or EIP-712) and server-side HMAC/secret handling
We are still working on the flow of Unity Integrations for Miniapp, We will be providing the Unity WebGL Integration Kit soon

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Farcaster Miniapp Integration Flow

  • Farcaster Miniapps provide native in-app wallet connections (e.g., Wagmi, Privy, or custom connectors).
  • The Unity WebGL build runs seamlessly inside the Farcaster frame, maintaining wallet context and session continuity.
  • All in-game and external transactions follow the same x402-compliant payment logic, powered by the Gx402 middleware.
  • Gx402 acts as a facilitator layer, verifying Solana transactions and unlocking protected APIs or in-game assets post-payment.
  • This architecture ensures cross-platform compatibility, allowing the same Unity game to run on Farcaster, Telegram, or browser-based miniapps with minimal code changes.

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Farcaster Miniapp Intergration & Flow

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EVM Flow

This guide explains how to integrate Unity WebGL games with Farcaster Miniapps.
Your setup uses:
  • Unity (WebGL) → gameplay & event triggers
  • TypeScript Web Layer → bridge between Unity and Farcaster
  • gx402 → connects Unity ↔ TypeScript/x402 payments
  • Farcaster Evm Provider → signs & sends transactions inside Farcaster

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Overview

  • Rather than manually wiring every payment flow, x402 provides a payment-middleware + client wrapper that handles wallet connection, payment prompt, and protected API calls.
  • The wallet integration is typically handled by an EVM-wallet library such as wagmi (or OnchainKit) — the miniapp template already includes this.
  • The miniapp template auto-detects when it’s running inside Farcaster, and the frame SDK ensures the wallet and environment are set up appropriately.
  • You protect routes via payment middleware. If a user calls a protected endpoint without paying, the server returns HTTP 402 (“Payment Required”) with details. Your client then triggers a wallet payment and retries the call with proof.
  • Using a bridge between Unity + Typescript + Mini-App we call x402 from our deployed server and Gx402

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Unity Implementation

For now we will be using the same approach for build as of Unity Integration section
We will be providing the code snippet to connect the In-App wallet inside the game as repo is still under construction

 ## Folder Structure (For Unity WebGL build)
```bash
farcaster-miniapp/
├── app/
│   ├── .well-known/
│   │   └── farcaster.json
│   ├── api/
│   │   ├── notify/
│   │   ├── protected/
│   │   └── webhook/
│   ├── globals.css
│   ├── layout.tsx
│   ├── page.tsx
│   ├── providers.tsx
│   ├── theme.css
|   ├── Bridge.ts
│   └── UnityBuild.tsx
│
├── lib/
│
├── node_modules/
│
├── public/
│   └── unity/
│       ├── Build/
│       │   ├── Build.data
│       │   ├── Build.framework.js
│       │   ├── Build.loader.js
│       │   ├── Build.wasm
│       └── TemplateData/
│           └── index.html
│
└── package.json