clipx

LAN clipboard sync for macOS. Copy on one Mac, paste on another. Instantly.

No cloud. No account. No Apple ID. No flaky Universal Clipboard.

  ┌──────────────────┐                  ┌──────────────────┐
  │  MacBook         │    UDP :9877     │  iMac            │
  │                  │ ──────────────►  │                  │
  │  clipx           │                  │  clipx           │
  │  192.168.0.5     │ ◄──────────────  │  192.168.0.6     │
  └──────────────────┘                  └──────────────────┘
       copy ⌘C                             paste ⌘V

Install

brew install gomantics/tap/clipx

Or with Go:

go install github.com/gomantics/clipx/cmd/clipx@latest

Pre-built binaries for macOS (Intel & Apple Silicon) are on the releases page.

Quick start

1. Pair your Macs

# On Mac A (192.168.0.5):
clipx pair 192.168.0.6

# On Mac B (192.168.0.6):
clipx pair 192.168.0.5

2. Install and run (on both Macs)

clipx install

This adds a firewall exception, creates a LaunchAgent, and starts clipx. Done. Copy on one, paste on the other.

Tip: Disable Apple's Universal Clipboard — it will fight with clipx. System Settings → General → AirDrop & Handoff → Handoff → Off

Commands

Command	Description
clipx	Start the daemon (foreground)
clipx pair <ip>	Add a peer
clipx unpair <ip>	Remove a peer
clipx peers	List peers and their status
clipx install	Install LaunchAgent + firewall exception
clipx uninstall	Remove LaunchAgent
clipx status	Show status and recent logs
clipx update	Self-update to latest release
clipx version	Print version

Adding more Macs

Pair each new Mac with every existing one:

# On the new Mac:
clipx pair 192.168.0.5
clipx pair 192.168.0.6
clipx install

# On each existing Mac:
clipx pair 192.168.0.7
clipx uninstall && clipx install

Configuration

Peers live in ~/.config/clipx/config.json:

{
  "peers": ["192.168.0.5", "192.168.0.6"]
}

How it works

• UDP unicast on port 9877 — no multicast, no firewall headaches
• Explicit pairing — clipx pair <ip>, no flaky auto-discovery
• SHA-256 dedup — prevents clipboard ping-pong loops between nodes
• Chunked transfer — content >1300 bytes is split into UDP-safe chunks, up to 10 MB
• Triple send — small payloads sent 3x for UDP reliability

Wire format

[6B magic "CLIPX2"] [1B type] [8B nodeID] [payload]

Type	Byte	Purpose
Clipboard	C	Clipboard content (single packet)
Chunk	K	One chunk of large content
Ping	P	Health check
Pong	A	Health check response

Troubleshooting

Clipboard doesn't sync — Run clipx peers to check connectivity. Run clipx in foreground on both machines to see logs.

"address already in use" — Another instance is running. pkill clipx or clipx uninstall && clipx install.

Firewall blocking — Re-run clipx install or manually: sudo /usr/libexec/ApplicationFirewall/socketfilterfw --unblockapp $(which clipx)

Logs — tail -f ~/Library/Logs/clipx.log

Contributing

Contributions welcome! See CONTRIBUTING.md.

License

MIT — see LICENSE.