Petal

Low-latency, multi-window screensharing for macOS and Windows — built for small engineering syncs.

When someone shares a window, it appears on your desktop as a real, movable, borderless native window — not a tile locked in a meeting grid. Move it, stack it, keep it docked next to your editor while the call keeps going.

User docs: petal.live/docs — install, permissions, sharing, remote control, self-hosting. This README is for people who want to build or contribute.

Status

Petal is young. The macOS app is signed, notarized, and in daily use, but the project is pre-1.0: interfaces change, some features are further along than others, and remote control in particular should be treated as early. Windows support is early: basic sharing (WGC capture, D3D11 compositor, Media Foundation camera, WASAPI audio, rooms) works, but the platform is still incomplete and buggy and under active development. An x86-64 Windows NSIS installer is published unsigned for Authenticode and may trigger SmartScreen; macOS remains the more mature client. See docs/VALIDATION.md for an honest account of what has been verified and what has not.

Download

Always serves the latest signed, notarized universal build.

The Windows installer is currently unsigned for Authenticode and may trigger SmartScreen. Its automatic updates still use Tauri's updater signature.

• macOS requires: macOS 13 (Ventura) or later
• macOS universal: Apple Silicon and Intel

Install (macOS)

1. Click Download above to get Petal.dmg.
2. Open the DMG and drag Petal into Applications.
3. Launch Petal. On first run it walks you through granting:
   • Screen Recording — required, to share windows
   • Microphone — required, for audio
   • Camera — optional, for your webcam
   • Accessibility — optional, only if you want to give/receive remote control

That's it. Petal is notarized, so macOS opens it without any Gatekeeper warnings.

Features

• Windows, not tiles — each shared window is an independent native window on your desktop that you can move, resize, and arrange freely.
• Share several windows at once — from a hover pill on any window, a picker, or a global shortcut (⌘⌃⇧S). Each is its own hardware-encoded H.264 stream.
• Telepointers and drawing — everyone's cursor shows live over the window they're pointing at, and anyone can sketch on a shared window; strokes fade after ten seconds.
• Remote control — hand a teammate control of a shared window; their clicks and keystrokes are injected without stealing your focus. Requires Accessibility permission, and by default every request raises a consent prompt on your screen (Ask me each time; switch to Allow automatically or Off in Settings). See docs/remote-control-trust-model.md.
• AI chat on a shared window (opt-in) — anyone in the meeting can open a live Gemini session about a window being shared: it sees the window, hears the room over push-to-talk, and can act on the window only with the sharer's explicit approval. Off by default; bring your own key or use the hosted mint.
• Rooms & invites — persistent named rooms, one-click join, and petal://join/<code> invite links with live presence.
• Audio — mic with echo cancellation and noise suppression, real mute from the gallery, floating pill, or menu bar, and device hot-swap.
• Fits your workflow — the gallery collapses into a floating pill (⌘⌃⇧P brings it back), and a menu-bar pill shows mic state, participant count, and one-click leave.
• Resilient — reconnects across network changes and re-publishes your shares automatically.

There's also a browser client (web-harness/, deployed at meet.petal.live) so people without the app can join from a browser by code or invite link.

Build from source

Build-host requirements are stricter than runtime requirements. Petal runs on macOS 13+, but building it currently needs the macOS 26 SDK (Xcode 26.x): the apple-metal crate, pulled in transitively by our vendored screencapturekit, uses Metal APIs that do not resolve against earlier SDKs. On an older SDK the Swift bridge fails to compile.

Prereqs:

• macOS with Xcode 26.x (full Xcode, not just Command Line Tools)
• Node 20+
• Rust stable
• livekit-server (brew install livekit) for local meetings

# 1. local SFU
livekit-server --dev              # ws://localhost:7880 (devkey/secret)

# 2. the desktop app
cd apps/desktop
npm install
PETAL_BACKEND_URL= \
LIVEKIT_URL=ws://localhost:7880 LIVEKIT_API_KEY=devkey LIVEKIT_API_SECRET=secret \
  npm run dev:clean

The empty PETAL_BACKEND_URL= selects the debug build's local token mint, so your local LiveKit credentials are the ones used. There is no hosted default: a build that never sets PETAL_BACKEND_URL has no token backend at all, which is deliberate — a build from this source should never quietly use someone else's service. Point it at your own with docs/SELF_HOSTING.md.

Use npm run dev:clean (not tauri build) for GUI iteration — it keeps the Screen Recording grant stable across rebuilds. App logs live at ~/Library/Logs/Petal/petal.log. Verify a change with scripts/ci-local.sh.

Windows

Prereqs: Windows 10/11, WebView2 runtime (ships with Windows 11), Node 20+, Rust stable.

cd apps/desktop
npm install
npm run tauri dev

No CLT/Swift recipe or notarization applies on Windows; scripts/ci-local.sh is macOS-only (run npm run check && npm test + cargo test --lib instead).

Builds from source are unsigned, and are not the same artifact as the notarized download above.

To run Petal against your own LiveKit and token backend rather than the hosted one, see docs/SELF_HOSTING.md.

Repo layout

petal/
  apps/desktop/    the desktop app (macOS + Windows) — Tauri 2 (Rust core + Svelte 5 SPA)
  web-harness/     the browser client
  backend/         token/rooms API + release distribution (Vercel)
  shared/          UI + logic shared by the desktop app and the browser client
  contracts/       cross-language wire fixtures
  docs/            architecture, contracts, testing, and self-hosting guides
  scripts/         build, verification, and CI helpers
  sbom/            CycloneDX bill of materials + license audit
  site/            the documentation site

Stack

Tauri 2 (Rust core, WKWebView on macOS / WebView2 on Windows) · Svelte 5 + TypeScript · ScreenCaptureKit capture on macOS / Windows.Graphics.Capture on Windows · Media Foundation camera + WASAPI audio on Windows · VideoToolbox H.264 on macOS / D3D11 receiver compositor on Windows · WebRTC over an SFU (LiveKit).

Contributing

Start with CONTRIBUTING.md, and read docs/ENGINEERING.md before touching native window code — it documents crash classes that are easy to reintroduce and unpleasant to debug.

• Architecture: docs/ARCHITECTURE.md
• Wire contracts: docs/CONTRACTS.md
• Testing: docs/TESTING.md
• Security policy: SECURITY.md
• What Petal sends over the network: PRIVACY.md

License

Apache-2.0 — see LICENSE, NOTICE, and THIRD_PARTY_NOTICES.md.

The Petal name and logo are not covered by that grant; see TRADEMARKS.md.