NearDrop
LiveNearDrop is a browser-based P2P file sharing PWA. Devices on the same Wi-Fi discover each other automatically; a Fastify + Socket.io signaling server brokers the WebRTC handshake, then steps aside. Every byte travels through a direct RTCDataChannel with mandatory DTLS-SRTP encryption. Transfers are chunked and flow-controlled for large files, with IndexedDB buffering and SHA-256 verification on arrival. Also supports P2P text chat, voice notes, clipboard sharing, and folder send via JSZip. Cross-network pairing works via a 6-character room code or QR code. Installable as a PWA with a share target so the OS share sheet can push files directly into the app.
Next.jsTypeScriptWebRTCSocket.ioFastifyTailwind CSSshadcn/uiIndexedDBPWA
- Problem
- AirDrop only works between Apple devices. Every cross-platform alternative requires an account, a download, or routes your files through a third-party server. There was no friction-free, privacy-respecting way to transfer files between arbitrary devices.
- Solution
- Built a PWA where the browser is the transfer endpoint. A minimal signaling server brokers the WebRTC handshake (SDP + ICE), then steps out. All data flows peer-to-peer through an RTCDataChannel. Large files are chunked with a 16 MB buffer threshold and spilled to IndexedDB to avoid memory issues. Room codes, QR codes, and optional password protection handle cross-network pairing.
- Challenges
- Keeping large transfers stable required careful flow-control: pausing the send loop when the RTCDataChannel buffer exceeded 16 MB and resuming on the bufferedamountlow event. Deciding between in-memory reassembly and IndexedDB based on file size, without blocking the UI thread, was the trickiest part of the transfer pipeline.
- Outcome
- A fully functional cross-platform file transfer PWA with zero install friction. Handles arbitrary file sizes, whole folders, voice notes, clipboard, and real-time chat, all peer-to-peer and end-to-end encrypted.