Zeronet

A local-network web application that lets devices on the same WiFi or hotspot discover each other, connect, chat, and share files without internet.

Structure

zeronet/
├── frontend/   # React 18 + Vite, Tailwind, Framer Motion
└── backend/    # Node.js, Express, Socket.IO, Bonjour (mDNS)

Quick Start

Backend

cd backend
npm install
node server.js

Server runs at http://0.0.0.0:3001 (all interfaces so other devices can reach it).

Frontend

cd frontend
npm install
npm run dev

Open the URL shown (e.g. http://localhost:5173). On another device on the same network, use the same backend URL (e.g. http://<server-ip>:5173 if you use the same machine, or run frontend elsewhere and set the server in the UI).

How It Works

1. Discovery
   The backend advertises itself via mDNS/Bonjour. The frontend discovers servers by scanning common LAN ranges (192.168.43.x, 172.20.10.x, 192.168.1.x) and calling /api/info.

2. Connection
   Device A discovers Device B and clicks Connect. B gets a popup to Accept or Reject. On accept, WebRTC signaling (offer/answer/ICE) is relayed through Socket.IO.

3. Chat & files
   After the WebRTC data channel is open, chat and file transfer are direct P2P; the server is only used for signaling.

4. File sharing
   Files are split into 64KB chunks and sent over the data channel with metadata (fileId, chunkIndex, totalChunks). The receiver reassembles and allows download.

Routes

• / — Lobby (device discovery, connect)
• /chat/:peerId — Chat room with a specific peer

Tech Stack

Frontend: React 18, Vite, Tailwind CSS v3, Framer Motion, React Router v6, Lucide React, date-fns
Backend: Node.js, Express, Socket.IO v4, bonjour-service, helmet, cors

Requirements

• Devices on the same WiFi or hotspot
• No internet required after loading the app (except optional STUN: stun.l.google.com for NAT)
• Backend must be reachable at the same IP/port from all devices (e.g. run on a machine that others can access)