targetBridge

TargetBridge

Apple dropped Target Display Mode in late 2014 with the 5K iMac — and it never came back.

TargetBridge brings it back via software, streaming your screen at up to 5K over a direct Thunderbolt connection, e.g. to an iMac.

It's free and open source software, no subscription and no dongle required.

If it is useful to you, spread the news and give us a ⭐ on GitHub.

Sponsoring the TargetBridge project is also very welcome:

TargetBridge 3.1

TargetBridge 3.1 keeps the multi-Mac workspace foundation from 3.0 and adds scriptable remote connection controls for the Sender:

• mirror mode and extended desktop mode
• multiple receivers from one sender
• experimental Network Link transport in addition to Thunderbolt Bridge
• streamed system audio
• shared JSON localization for Sender and Receiver
• official manifest-based addons
• Input Dockstation with master/slave keyboard and mouse control
• text clipboard sync tied to the active input master
• remote brightness control from the sender
• automatic receiver discovery and extended-layout restore
• remote connection automation via URL scheme, CLI wrapper, launch args, and SSH recipes

Feature Guides

• Overview hub: docs/Features.md
• Mirror mode and Extended Desktop: docs/Features.md#display-modes
• Multi-receiver layouts: docs/Features.md#multi-receiver-workflows
• Network Link (experimental): docs/Features.md#network-link-experimental
• Audio Relay: docs/Features.md#audio-relay
• Input Dockstation, clipboard sync, and master/slave roles: docs/Features.md#input-dockstation
• Remote brightness control: docs/Features.md#remote-brightness-control
• Remote connection & automation (URL scheme, launch args, SSH, login/wake): docs/Automation.md
• Shared translations and language files: docs/Features.md#shared-translations
• Thunderbolt networking extras (SSH/SFTP, file sharing, Internet Sharing): docs/Features.md#thunderbolt-networking-extras

Core Features

• Sender can stream either a mirrored desktop or an extended virtual display. See Display Modes.
• One sender can drive multiple receiver Macs over separate cables. See Multi-Receiver Workflows.
• Stream profiles range from 2560 x 1440 to 5120 x 2880 with H.264/HEVC selection based on capability. See Display Modes.
• Receiver discovery is automatic over Bonjour. Extended-display arrangement is remembered per receiver when possible. See Display Modes.
• Thunderbolt Bridge remains the primary low-latency path, with Network Link available as an experimental addon-gated transport. See Network Link.

Official Addons

TargetBridge now has a conservative manifest-based addon system. Official manifests ship with the app, and user manifests can be imported from the settings UI.

• Network Link: local Ethernet/Wi-Fi transport path for the same display pipeline. See docs/Addons.md#official-addons and Network Link.
• Audio Relay: streamed system audio from sender to receiver. See docs/audio.md and docs/Addons.md#official-addons.
• Input Dockstation: keyboard/mouse relay, master/slave roles, slave switching, and text clipboard sync. See docs/Addons.md#input-dockstation and Input Dockstation.

Requirements

• Sender: Apple Silicon Mac (M1 or later), macOS 14 Sonoma or later
• Receiver: Intel or Apple Silicon Mac, macOS 11 Big Sur or later
• Thunderbolt cable
• See also docs/Hardware.md for hardware details, tested cables, adapters, and Thunderbolt networking ideas.

Download

→ Download latest release (pre-built apps, no Xcode needed)

• TargetBridge-arm64.app.zip — Sender (for Apple Silicon Macs)
• TargetBridge-Receiver-arm64.app.zip — Apple Silicon Receiver (use machine as monitor for sender)
• TargetBridge-Receiver-x86_64.app.zip — Intel Receiver (use machine as monitor for sender)

Unzip and double-click. On first launch, grant Screen Recording permission to the sender.

If you build from source, app outputs go into build/ folder.

"App is damaged" warning? macOS quarantines unsigned apps downloaded from the browser. Run this in Terminal, then try again:

xattr -cr ~/Downloads/TargetBridge-arm64.app
xattr -cr ~/Downloads/TargetBridge-Receiver-arm64.app
xattr -cr ~/Downloads/TargetBridge-Receiver-x86_64.app

Permissions

• Sender usually needs Screen Recording.
• Input Dockstation may also require Accessibility and Input Monitoring, depending on the active role.
• Receiver may require Accessibility or Input Monitoring when it participates in input relay.
• In practice, Input Dockstation is a two-sided feature: one Mac captures input, the other injects it, so permissions may be needed on both Sender and Receiver.
• See docs/Addons.md#input-dockstation for the permission matrix.

Quick start

• Italian: docs/QuickStart-IT.md
• English: docs/QuickStart-EN.md
• 中文: docs/QuickStart-ZH.md
• Translation guide: docs/Translations.md

Detailed Documentation

• Feature overview: docs/Features.md
• Remote connection & automation: docs/Automation.md
• Addon manifests and capability model: docs/Addons.md
• Audio transport internals: docs/audio.md
• Hardware, cables, adapters, and Thunderbolt Bridge networking: docs/Hardware.md
• Translation workflow: docs/Translations.md
• Binary verification: docs/verify-binaries.md

Licensing and brand

TargetBridge source code is available under the MIT License. Please preserve the required copyright and license notices when redistributing copies or substantial portions of the software.

Project branding and commercial use are handled separately from the source code license. For now, the canonical source-code license is:

• LICENSE

Screenshots

Sender (Apple Silicon Mac) — multi-session dashboard:

Sender — active mirrored stream (5K, HEVC):

Receiver (Intel iMac) — waiting for sender:

macOS Displays — extended desktop target:

macOS Displays — mirrored desktop target: