About SimStream

Use the iOS Simulator screen on a browser (mobile or not). Low-latency, limited dependencies.

Demo video

Dependencies

• Swift/Xcode
• idb_companion (brew install facebook/fb/idb-companion): send touch events to the simulator
• Python package manager (pip or uv) to run the idb Python bridge ()
• cloudflared (brew install cloudflared): needed to expose the stream to an agent like Claude. Skip with --no-tunnel if you only want a local URL.
• For streaming: Chrome 94+ or Safari 16.4+ (needs VideoDecoder)

Permissions

Grant both to Terminal (System Settings → Privacy & Security):

• Screen Recording — required to capture the Simulator window via ScreenCaptureKit.
• Accessibility — used to locate the device-screen rect inside the Simulator window so the macOS title bar is cropped out and touches map to the right device coordinates.

When running inside a MacOS VM, you can force-enable those permissions by modifying TCC.db (integrity protection needs to be disabled, it's the case on Tart VMs)

Installation (with agent skill)

npx skills add EliotAndres/SimStream

Installs a /stream-simulator skill into your coding agent. From then on, ask the agent to start SimStream (or paste an error) and it will handle setup, launch, permission prompts, and troubleshooting for you.

Installation (manual)

./install_idb.sh

Installs idb-companion via Homebrew and creates a Python venv for the touch bridge. Uses uv if present, otherwise falls back to python3 -m venv + pip.

Run

./start.sh              # default: serves http://localhost:3738 AND a Cloudflare tunnel
                        # URL so an agent (Claude, etc.) can open the stream remotely.
./start.sh --no-tunnel  # local only — skip cloudflared. Use when you're viewing
                        # from a browser on the same machine or LAN.

Notes (AI Generated)

• The Swift process disables Window → Show Device Bezels on launch (cleaner capture).
• A single Swift binary handles capture, H.264 encoding (hardware with software fallback), HTTP, and WebSocket — no separate signaling server.
• Touch events are forwarded to idb_companion over a persistent gRPC bridge (idb_touch_events_bridge.py).
• Override the port with PORT=xxxx swift run SimulatorStream.
• macOS VMs / Tart guests: VideoToolbox often creates an H.264 session but never delivers frames (kVTVideoEncoderNotAvailableNowErr). The encoder falls back to software H.264 after a few failed output callbacks. To skip hardware from the first frame, set SIMULATOR_STREAM_PREFER_SOFTWARE_ENCODER=1 (e.g. SIMULATOR_STREAM_PREFER_SOFTWARE_ENCODER=1 ./start.sh).