Workshop 05 — P2P Dropbox & WebRTC

Workshop 05 was about decentralized file transfer — no server storing your files, just direct browser-to-browser (or CLI-to-CLI) data channels.

Architecture

sender.ts ──── WebRTC DataChannel ───── receiver.ts
              ↕                  ↕
         CF Workers Signaling Server
         (wss://phd-signaling.laris.workers.dev/ws)

The signaling server (Cloudflare Workers) only exchanges connection metadata (SDP offers/answers, ICE candidates). Actual file data flows directly between peers via WebRTC DataChannel.

Key Components

Cloudflare Workers Signaling

// WebSocket upgrade + Durable Object for room coordination
const room = env.ROOMS.get(env.ROOMS.idFromName(peerId))
return room.fetch(request)

CLI Sender/Receiver

# Send a file
bun send.ts --peer alice myfile.pdf

# Receive
bun receiver.ts --name alice

AUTH_KEY Usage

The signaling server uses an AUTH_KEY for room authentication. This key is per-deployment and should never be posted publicly.

Key Learning

P2P is not serverless — it is server-minimal. The signaling server coordinates connection setup but touches zero bytes of actual data. Cloudflare Workers + WebRTC is the leanest possible architecture for P2P file transfer.

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