Screenshare

Share a screen. Talk it through. Keep everyone in the same room.

Peer-to-peer screen sharing, voice, camera and chat in your browser — with native capture on Windows and macOS.

Português · Website · Features · Run locally · Documentation

Get into a room

1. Open Screenshare in your browser or download the desktop app.
2. Enter your name. Leave the room code empty to create a room, or paste a code to join one.
3. Copy the room code from the conversation header and send it to the people you want to join.
4. Share your screen, enable your microphone or camera, and chat.

No account is required. The interface is currently in Brazilian Portuguese. Anyone with the room code can join; use it with people you trust.

What you can do

• Share screens and windows, with game, video, and code/text presets. Adjust frame rate (up to 60 fps), bitrate and the trade-off between sharpness and smoothness.
• Talk and use your camera independently of screen sharing. Choose devices, mute your microphone or output, and adjust another participant's volume.
• Follow multiple streams in a grid or focus on one with a preview rail. Hide the conversation when you need more space.
• Chat in the room, including earlier messages while the room remains active.
• Use native desktop capture with screen/window thumbnails, computer or application audio, tray controls, optional startup at login, and in-app updates for supported installations.
• Host your own server. Kotlin/Ktor handles rooms, text chat and WebRTC signaling; media uses a direct connection when possible, with TURN relay when needed.

Resolution, frame rate and audio availability depend on the source, browser, operating system, network and hardware. These are capture/encoder settings, not a performance guarantee.

Browser or desktop?

	Browser	Windows desktop	macOS desktop
Screen sharing, camera, voice and chat	Yes	Yes	Yes
Source selection	Browser picker	Native screens/windows and thumbnails	Native screens/windows and thumbnails
Shared audio	Browser/source dependent	Computer or selected application	Computer or selected application
Tray controls and startup at login	—	Yes	Yes
Distribution	Open the web app	x64 installer, MSI or portable EXE	Apple Silicon app archive and install script

Desktop builds use the same Kotlin/JS client and rooms as the browser. Windows builds are unsigned; macOS builds use ad hoc signing without notarization. See installation, permissions and platform limits.

See it in action

Watch the short demo or download the English-captioned MP4. The recording shows a real local browser session; it does not demonstrate native audio or measure streaming performance.

Screenshots show the current browser client in a local demo room, with a real WebRTC screen stream and sample conversation. The shared content is this repository's Kotlin protocol source.

Join or create a room	Tune your transmission

Run locally

Install JDK 21 (the build uses a Java 21 toolchain), then clone and run:

git clone https://github.com/RafaelrainBR/screenshare-kotlin-js.git
cd screenshare-kotlin-js
./gradlew :server-java:run

On Windows PowerShell, use .\gradlew.bat :server-java:run.

Open http://localhost:8080 in two tabs and join the same room. The task builds the browser client and serves it with the signaling server. The included Gradle wrapper manages Gradle and the Kotlin/JS Node/Yarn tools; the first build downloads dependencies. For screen sharing on another host, serve the app over HTTPS.

See development and tests for build commands and desktop prerequisites; see self-hosting for Docker, Fly.io and STUN/TURN configuration.

How it works

flowchart LR
    A["Browser / desktop A"] <-->|"WebSocket: rooms, chat, SDP and ICE"| S["Ktor signaling server"]
    S <-->|"WebSocket: rooms, chat, SDP and ICE"| B["Browser / desktop B"]
    A <-->|"WebRTC: screen, camera and audio"| B
    A <-.->|"When direct connectivity fails"| T["TURN relay"]
    T <-.-> B

Module	Responsibility
client/	Kotlin/JS interface, WebRTC, screen sharing, camera and voice
common/	Kotlin Multiplatform packet types shared by JS and JVM
server/	Ktor/JVM signaling, room membership and in-memory chat history
server-java/	JVM entry point, fat JAR, Docker and Fly.io configuration
desktop-native/	Desktop app in Rust and iced: tray, updater, WebRTC and encoders
desktop-capture/	Shared Rust capture: Windows DXGI/GDI/WASAPI and macOS ScreenCaptureKit/Core Audio

The UI uses local CSS, JavaScript and Barlow fonts. Dependency versions live in libs.versions.toml and the Cargo manifests.

Project status and contributing

Screenshare is under active development. Documentation describes the current source; the latest desktop release may lag behind master. Release assets and changes are listed on GitHub Releases.

Bug reports, platform testing and contributions are welcome. Start with CONTRIBUTING.md, check open issues, or read the documentation index.

Licensed under MIT.