Mac + Windows Input Sharing — One Keyboard & Mouse for Two PCs

If you have both a Mac and a Windows machine on your desk, driving both with a single keyboard and mouse is an immediate quality-of-life upgrade. Unlike a hardware KVM, software input sharing lets the cursor cross the screen edge and seamlessly switch input target — like a natural extension of a multi-monitor setup.

There are five options and the right answer depends on the case. This page is organized as: per-scenario recommendation → comparison matrix → Barrier walkthrough for the most common Mac+Win case.

TL;DR — One-line Recommendation per Scenario

Comparison Matrix

Clipboard sharing comes standard in Barrier/Synergy/Logitech Flow. Mouse Without Borders too. Universal Control: text only (use AirDrop for files).

Choose Up Front — Which One

Mac + Windows (the main case here)

For personal use: try Barrier → buy Synergy if unstable. Same operating principle (keyboard/mouse on server PC, input forwarded to client PCs).

If you use a Logitech mouse/keyboard on both, Logitech Flow is the answer — no separate SW and smoothest.

Same-Vendor Case

• Mac only: Universal Control. System Settings → Displays → Advanced → "Allow your pointer and keyboard..."
• Windows only: Mouse Without Borders. Install via Microsoft Store

Barrier Walkthrough — Mac (server) + Windows (client)

Server = the PC the keyboard and mouse are physically attached to. Either side can be server; usually the one with the more familiar key map. Here Mac = server, Windows = client.

1. Install

Mac (server):

brew install --cask barrier
# Or download .dmg from https://github.com/debauchee/barrier/releases

Windows (client):

winget install --id Debauchee.Barrier --silent
# Or download .msi from https://github.com/debauchee/barrier/releases

Barrier has had no active updates since 2022. macOS 15 (Sequoia) and newer sometimes have permission-dialog issues — consider Input Leap (Barrier's successor fork).

2. Same Network + Firewall

Both PCs need to be on the same LAN (typically same Wi-Fi/wired). Different subnets need routing or VPN.

Windows firewall:

# Allow inbound on Barrier's 24800
New-NetFirewallRule -DisplayName "Barrier" -Direction Inbound -LocalPort 24800 -Protocol TCP -Action Allow

macOS firewall:

If System Settings → Network → Firewall is ON, the first launch of Barrier.app shows an "Allow incoming connections" dialog — click Allow.

3. Mac Server Configuration

1. Launch Barrier → select Server radio
2. Click Configure Server...
3. Drag the monitor icon from top-right onto the grid → position Windows relative to Mac
4. Double-click the added screen → set Screen name to Windows's hostname (case sensitive)
   • Windows hostname: check with hostname
5. OK → click Start on the main window

4. macOS Permissions (essential, often missed)

macOS requires explicit consent for Barrier to intercept system events:

System Settings → Privacy & Security:

• Accessibility → Barrier ✅
• Input Monitoring → Barrier ✅
• Screen Recording → Barrier ✅ (needed for clipboard text)

Restart Barrier after adding permissions.

5. Windows Client Configuration

1. Launch Barrier → select Client radio
2. Server IP: Mac's IP (find with ipconfig getifaddr en0 on Mac, or System Settings → Network → Wi-Fi → Details → TCP/IP)
3. Start

6. Verify

Move the mouse on Mac past the screen edge → the cursor appears on Windows. The keyboard now types there too.

Clipboard: Copy on Mac with Cmd+C → paste on Windows with Ctrl+V. If it doesn't work, re-check macOS Screen Recording.

7. Auto-start

Mac: in Barrier Barrier → Save configuration as..., then add Barrier.app to System Settings → General → Login Items.

Windows: in Barrier File → Save configuration as..., then Settings → Apps → Startup → Barrier ON. Or use Barrier's Barrier → Auto start on boot.

Logitech Flow — Logi Mouse/Keyboard Users

If you have a Logitech mouse (MX Master, MX Anywhere) or keyboard (MX Keys) paired (Bluetooth or Unifying) on both PCs, Flow has almost no setup.

1. Install Logi Options+ on Both PCs

• Mac: brew install --cask logi-options-plus or logitech.com/options
• Windows: winget install Logitech.OptionsPlus

2. Enable Flow

Same LAN. Launch Logi Options+ on both → left menu Flow → both PCs auto-detected → drag the screen layout → enable.

3. Verify

Move cursor past the screen edge → switches to the other PC. Keyboard follows. Clipboard sharing toggle available.

Flow works only via Logitech input devices. Apple Magic Mouse / other vendors → Flow can't drive them — use Barrier.

Mouse Without Borders — Windows Only

Started as a Microsoft Garage project and absorbed into PowerToys. Windows ↔ Windows only.

Install

# Method 1: built into PowerToys (if you're already using it)
winget install Microsoft.PowerToys --silent
# → Launch PowerToys → left menu "Mouse Without Borders" → enable
 
# Method 2: standalone (older, only when PowerToys is unavailable)
winget install Microsoft.MouseWithoutBorders

Setup

1. Enable on first PC → a Security key appears (8 digits)
2. Enable on second PC → enter first PC's name + Security key
3. Auto-connects → screen layout auto-detected (left/right)

Very simple and stable. Excluding Mac, this is the #1 free pick.

Apple Universal Control — Mac (+ iPad) Only

For Mac/iPad signed into the same Apple ID, no separate install needed.

Enable

System Settings → Displays → Advanced... or AirPlay/Universal Control toggle:

• ✅ Allow your pointer and keyboard to move between any nearby Mac or iPad
• ✅ Push through the edge of a display to connect a nearby Mac or iPad
• ✅ Automatically reconnect to any nearby Mac or iPad

Same Apple ID + Wi-Fi/Bluetooth on → cursor at screen edge auto-connects.

Universal Control can't reach Windows. Mac↔Mac only.

Input Sharing ≠ File / Screen Sharing

This page only covers keyboard, mouse (+ clipboard text). Other domains use other tools:

To add screen sharing on top, Parsec + Barrier combo gives a near-game-streaming low-latency multi-OS setup.

Troubleshooting

Mouse Won't Cross to the Other Screen

• Same LAN? ping <peer IP> to check
• Firewall: inbound on 24800 (Barrier/Synergy default)
• In the server's screen grid, does the client screen name match the client's actual hostname?

macOS Sequoia (15) Barrier Permission Dialog Loop

Known issue. Options:

• Replace with Input Leap (better Sequoia compatibility)
• tccutil reset Accessibility org.deb.Barrier then re-grant
• Use Synergy 3 (paid)

Clipboard Doesn't Follow

• Barrier/Synergy: server needs Screen Recording (macOS) or clipboard access (Windows)
• Image/file clipboard: most input-sharing tools don't support — text only

Logitech Flow Can't Find the Other PC

• Same LAN? Guest Wi-Fi separates devices and breaks discovery
• Logi Options+ versions match? Version mismatch frequently breaks compatibility

Barrier Doesn't Reconnect After Drop

File → Auto-config disabled + on the client, set Server IP to a static IP instead of a hostname. Reserve the Mac's IP via DHCP.

Modifier Keys Behave Strangely Across OSes

Mac's Cmd and Windows's Ctrl are different keys. Remap via Barrier Configure Server → screen settings → Modifier keys, or Karabiner-Elements (Mac) / PowerToys Keyboard Manager (Windows).

Next Steps

• File sync: Syncthing — /multi-os/file-sync
• Screen/remote: Parsec, Sunshine+Moonlight — /multi-os/screen-sharing
• Mac initial setup: /mac/initial-setup
• Windows initial setup: /windows/initial-setup

References

• Barrier GitHub
• Input Leap — Barrier successor fork
• Synergy 3 (official)
• Logitech Flow guide
• Mouse Without Borders / PowerToys
• Apple Universal Control (official)

Changelog

• 2026-05-11 — Initial draft (devAlice M0 fourth seed)