⚡ LanBeam

Drop files to any device on your network. No accounts, no cloud, no trace.

How it works · 60-second start · Privacy · vs. alternatives

---

Your files should not take a detour through someone else's server to travel ten feet across your room.

LanBeam sends files directly between devices over an encrypted WebRTC connection. The server in this repo only introduces the two devices to each other — it never sees, stores, or logs a single byte of your files.

✨ Features

• 📤 Multi-file drag & drop with live progress, speed, and per-file download links
• 🔐 End-to-end encrypted — WebRTC DataChannels are encrypted with DTLS by default
• 🙈 Zero-knowledge server — signaling only; rooms auto-expire after 30 minutes
• 📱 Phone-friendly — receiver joins via QR code or a 6-character code, no app install
• 💬 Send-a-note — fire a short text message alongside your files
• 🪶 No build step — vanilla JS, one tiny Node server, one npm dependency (ws)
• 🌐 Works beyond your LAN — STUN-assisted NAT traversal for transfers over the internet

🚀 60-second start

git clone https://github.com/DhanushNehru/lanbeam.git
cd lanbeam
npm install
npm start

Open the printed Network URL (e.g. http://192.168.1.5:3000) on both devices:

1. Sender → Send files → pick files → a 6-character code + QR appears
2. Receiver → Receive files → enter the code (or scan the QR) → Accept
3. Files fly device-to-device, encrypted. Done.

Want it on the internet, not just your LAN? Deploy the same server.js anywhere Node runs (a $4 VPS, Fly.io, Railway…) — the privacy guarantees don't change, because files still never touch the server.

🔒 Privacy

	LanBeam	Typical "free" transfer sites
Files pass through a server	❌ Never	✅ Yes — that's their business model
Account required	❌	✅ Usually
File size limits / expiry upsells	❌	✅
Metadata logged	❌ (rooms are in-memory, auto-expire)	✅
Open source, auditable	✅	❌

Threat model in one line: the only thing an attacker running the signaling server can learn is that two devices connected — never what they sent.

🛠 How it works

 Sender (browser)                    Signaling server (Node)              Receiver (browser)
      │                                        │                                   │
      │── create room ────────────────────────▶│                                   │
      │◀──────────── 6-char code ──────────────│                                   │
      │                                        │◀────────── join(code) ────────────│
      │◀──────────── peer-joined ───────────────│                                   │
      │── SDP offer ──────────────────────────▶│── SDP offer ─────────────────────▶│
      │                                        │◀────────── SDP answer ───────────│
      │◀──────────── SDP answer ───────────────│                                   │
      │  ═══════════ encrypted WebRTC DataChannel (DTLS) ═══════════════════════▶ │
      │  ─────────────── file chunks (16 KB) ──────────────────────────────────▶ │

1. Signaling (WebSocket): exchange of SDP offers/answers and ICE candidates, keyed by room code.
2. Transfer (WebRTC DataChannel): chunked binary transfer with backpressure, progress, and reassembly — entirely peer-to-peer.

🗺 Roadmap

• Pairing via WebRTC mDNS — zero server at all on the same network
• Folder transfer (zip on the fly)
• Resume interrupted transfers
• E2E-encrypted text chat alongside files
• Desktop tray app (Tauri)

Have an idea? Open an issue — good ideas get built fast here.

🤝 Contributing

PRs welcome. Keep it dependency-light and privacy-first:

npm install
npm start   # http://localhost:3000

No linter, no framework, no build — if your change needs a bundler, it's probably too big.

📄 License

MIT © Dhanush Nehru — see LICENSE.

---

If LanBeam saved you from uploading a file to a sketchy site, consider giving it a ⭐ — it helps others find it.