Beacon turns your Mac's screen into a stream your iPhone can watch.
It is a macOS menu bar app that captures your display and system audio and sends them to the Beam iOS app over your local network. No cables, no cloud, no account. The video never leaves your network.
Free, signed, and notarized. Pair it with Beam on the App Store on your iPhone and you are streaming in about a minute.
Mac to iPhone is the one screen-mirroring direction Apple has never shipped, so the features people find while searching all point the wrong way:
- AirPlay — an iPhone can send AirPlay but never receive it. A Mac can AirPlay to an Apple TV, an AirPlay-compatible TV, a HomePod for audio, or another Mac running AirPlay Receiver. Never to an iPhone. "Reverse AirPlay" isn't a thing.
- Sidecar — turns an iPad into a second Mac display. It has never supported iPhone.
- iPhone Mirroring (macOS Sequoia and later) — puts your iPhone on your Mac. Opposite direction.
Beacon plus Beam covers that gap: your Mac's screen and audio, on your phone, over your own WiFi.
Worth being clear about the limit — this is a viewer, not a remote control. It shows your Mac and plays its audio; it does not send touch or keyboard input back. If you need to actually operate the Mac, you want a remote desktop tool instead.
More detail: why AirPlay can't do this · every Mac mirroring path compared · setup guide
Why the source is here. Beacon records your screen and your audio, which is about as much trust as you can ask of a piece of software. Rather than ask you to take our word for what it does with that, the code is public so you can check. Most people should just grab the DMG above, it is the same app, signed and notarized, and it updates itself.
One difference from the shipped build, so you do not have to find it yourself. Beacon 1.2.1 on the download link contains dormant, non-functional code for forwarding an iPhone-paired game controller to the Mac. It cannot do anything: creating a virtual gamepad needs Apple's
com.apple.developer.hid.virtual.deviceentitlement, which has been requested and not granted, and the feature has therefore never been tested end to end. Rather than publish code nobody can run or verify, it is left out here and comes back once the entitlement lands.StreamSessionstill recognises controller packets and drops them, which is why you will see.inputreferred to inProtocol.swift.
| Capture | ScreenCaptureKit for both display frames and system audio |
| Encode | VideoToolbox, hardware accelerated H.264. Never falls back to software encoding |
| Transport | Network.framework over TCP, on your LAN only |
| Discovery | Bonjour, advertising _beam._tcp |
| Pairing | Device keys held in the macOS Keychain |
| Idle cost | Near zero. No polling and no timers when you are not streaming, just a Bonjour listener |
Nothing is uploaded anywhere. There is no telemetry in Beacon, no account system, and no server in the path between your Mac and your phone.
- macOS 14 Sonoma or later
- Screen Recording permission, which macOS prompts for on first launch
- An iPhone on the same network running Beam
You do not need to build Beacon to use it, the DMG is the easy path. But if you want to audit or modify it:
git clone https://github.com/kevinerikjs/beacon-macos.git
cd beacon-macos
open BeamHost.xcodeprojSelect the BeamHost scheme, choose My Mac as the destination, and Run. Beacon appears in the
menu bar. Xcode 15 or later is required.
ScreenCaptureKit and real network streaming cannot be exercised in a simulator, and there is no Mac simulator anyway. Everything here has to be tested on real hardware, with a real iPhone at the other end.
BeamHost/
├── BeamHostApp.swift # Entry point, menu bar only (LSUIElement)
├── AppState.swift # Central observable state
├── Capture/
│ ├── ScreenCapture.swift # ScreenCaptureKit wrapper
│ ├── VideoEncoder.swift # VideoToolbox H.264 hardware encoder
│ ├── AudioEncoder.swift # Float32 PCM audio capture
│ └── VideoQualityManager.swift
├── Network/
│ ├── StreamServer.swift # TCP server, manages client sessions
│ ├── StreamSession.swift # Per-client stream session
│ └── Protocol.swift # Wire protocol, kept in sync with beam-ios
├── Pairing/
│ ├── PairingManager.swift
│ └── KeyStore.swift # Keychain-stored paired device credentials
├── MenuBar/
│ └── StatusItemView.swift
└── Settings/
└── SettingsView.swift
Network/Protocol.swift is shared in spirit with
beam-ios. Changing one side without the other will break
streaming, so protocol changes need to land in both repos together.
Issues and pull requests are welcome. A few things worth knowing before you start:
- Apple frameworks only. No third-party streaming or networking libraries.
- Swift concurrency (
async/await, actors) for anything asynchronous. - Test on real hardware. A PR that has only been compiled has not been tested.
- Larger changes are best discussed in an issue first, so you do not spend a weekend on something that does not fit the roadmap.
Contributions require agreeing to a short Contributor License Agreement , which is one line in your PR description. That document explains why it is needed, and the short version is that it is what keeps the dual licensing below possible.
| Document | What it covers |
|---|---|
| SECURITY.md | How to report a vulnerability privately, and which parts of Beacon are worth looking at |
| LICENSE | The AGPL-3.0 text |
| COMMERCIAL-LICENSE.md | Using Beacon without the AGPL obligations, and how to arrange that |
| CLA.md | The one line contributors add to a PR, and why it is needed |
| CODE_OF_CONDUCT.md | How people are expected to behave here |
| CLAUDE.md | Architecture rules, coding conventions, and the release runbook |
Found a security problem? Do not open an issue. Read SECURITY.md and mail support@beamscreen.app instead.
Beacon is dual licensed.
By default it is AGPL-3.0. You can use it, study it, modify it, and redistribute it, including commercially. What the AGPL asks in return is that if you distribute Beacon or something derived from it, you publish your source under the AGPL too.
A commercial license is available if you want to build on Beacon without those source disclosure obligations, for instance inside a closed source product. Terms are negotiable.
If that is you, mail support@beamscreen.app with the subject
Commercial license and a paragraph on what you are building. See
COMMERCIAL-LICENSE.md for the full picture.
The Beam and Beacon names, logos, and icons are not covered by the AGPL grant. Fork the code freely, but please ship it under your own name.
Copyright © Kevin Erik Iin.
Releases are cut manually. The signing, notarization, DMG, and Sparkle appcast steps are documented
in CLAUDE.md under Release Deployment, and the runbook reads its Apple
credentials from the environment:
export ASC_KEY_ID=... # App Store Connect API key id export ASC_ISSUER_ID=... # App Store Connect issuer id export ASC_KEY_PATH=... # path to the AuthKey_*.p8, never committed
DMGs are published to beacon-macos. The download URL in this README always resolves to the newest release automatically, so it does not need updating per release.