Latest Release: v1.0.0

LynxScreen: The open-source cross-platform screen sharing

LynxScreen is an open-source, cross-platform desktop application for peer-to-peer screen sharing, built with Electron and Svelte. It enables real-time screen sharing between two peers using WebRTC — no server required. Connection signaling is handled entirely through compact lynxscreen:// URLs exchanged out-of-band (e.g., via chat or email).

Figure 1: LynxScreen main interface showing the connection setup screen.

LynxScreen follows a layered Facade pattern for WebRTC:

┌─────────────────────────────────────────────┐
│              Svelte Stores                  │ 
│         (reactive UI state)                 │
├─────────────────────────────────────────────┤
│          ConnectionManager                  │  Orchestrator: phases, locking, URL encode/decode
├─────────────────────────────────────────────┤
│            WebRTCService                    │  Facade: unified API
├──────────┬──────────────┬───────────────────┤
│ PeerConn │ DataChannel  │  MediaStream      │  Sub-services
│ Service  │ Service      │  Service          │
├──────────┴──────────────┴───────────────────┤
│           Browser WebRTC APIs               │  RTCPeerConnection, getUserMedia, getDisplayMedia
└─────────────────────────────────────────────┘

• MediaStreamService — Acquires and manages audio/display streams
• PeerConnectionService — Wraps RTCPeerConnection (SDP, ICE, tracks)
• DataChannelService — Manages cursor position and ping data channels
• WebRTCService — Facade exposing a single API surface to the session layer
• ConnectionManager — Orchestrates the full connection lifecycle (init → offer → answer → connect → disconnect)

• Serverless P2P — Peers connect directly via WebRTC. SDP offer/answer is encoded into compact lynxscreen:// URLs exchanged out-of-band (chat, email, etc.).

• Real-Time Performance — Leverages WebRTC technology for low-latency screen sharing. As a serverless solution, Enable microphone on connect cannot be toggled during an active session if not configured at connection start.

• No Account Required — Simple setup with no sign-up, login, or account creation required. Just exchange URLs to establish a connection.

• No Server Storage — No data is ever stored on any server. Only a direct peer-to-peer connection exists between you and the screen sharing participant.

• Cross-Platform — Builds for macOS (.dmg), Windows (.exe), and Linux (.AppImage / .deb).

• Node.js v24.13.0+ (see .node-version)
• npm (comes with Node.js)
• macOS / Windows / Linux for development and packaging

This app uses public STUN servers (e.g., stun:stun.l.google.com:19302) by default to establish direct peer-to-peer connections. For the best experience, both peers should be on the same local network or behind STUN-compatible NAT.

You can optionally add your own TURN server in the app settings for improved connectivity across restrictive networks.

# Clone the repository
git clone https://github.com/qzhao19/LynxScreen.git
cd LynxScreen

# Install dependencies
npm install

# Start development (Vite dev server + Electron)
npm run dev

The app opens automatically. Vite provides hot module replacement for the Svelte renderer; the main/preload processes rebuild on save.

Output goes to the release/ directory. See electron-builder.yml for full packaging configuration.

# Or target a specific platform
npm run electron:build:mac
npm run electron:build:win
npm run electron:build:linux

# Unit tests
npm test

# E2E tests (full P2P connection flow with mocked WebRTC)
npm run test:e2e

# Coverage report
npm run test:coverage

Tests are located in tests/:

• tests/unittests/ — Unit tests for each service and utility
• tests/e2e/ — End-to-end P2P connection flow tests

This project is licensed under the MIT License - see the LICENSE file for details.