Open Source · macOS 14+
See what's using your ports.
Kill it in one click.
Quick access to all listening processes, with the working directory it was launched from. Menubar indicator when new ports open. Click to open/copy URL or kill process.
- Native Swift 6 · no Electron
- Signed & notarized
- Universal — Apple Silicon & Intel
- Zero telemetry · zero network
The port is in use. But what's using it?
You ran npm run dev. It failed. "Port 3000 is already in use."
You vaguely remember spinning up a Next.js project yesterday — in a tab
you've since closed. Now you're typing lsof -i :3000,
copying a PID, running kill -9, and guessing which process to kill.
This gets old, fast. So I made Port Watcher.
One icon. Everything you need.
Port Watcher lives in your menu bar, and changes colors when new ports open or close.
Click the menu bar icon
Every TCP listener owned by your user, sorted by port, refreshed every 5 seconds.
Scan the list
Port, command, PID, uptime, and the directory it was launched from — at a glance.
Kill what you don't need
Click for a polite SIGTERM. Right-click for SIGKILL. The list updates immediately.
Notices what you wouldn't.
Port Watcher doesn't just list ports when you ask. It runs in the background and tells you when something changes — the icon flashes when a port appears or dies, and turns orange when a process you've never seen before starts listening.
- Icon flashes on port changes — even with the popover closed
- Orange highlight on unfamiliar commands — spot the rogue Electron app
- Acknowledge list — one click marks the new processes as "I know about these now"
- Ignore list — VPN, Spotify, Ollama, etc (always listen, expected)
Built around how developers actually work.
A focused replacement for lsof -iTCP -sTCP:LISTEN and kill -9.
Light-weight: under 500KB, zero depencdencies. Built in Swift.
Dev Servers filter
One click hides system noise. Shows only the common dev-server ranges — 3000s, 4000s, 5000s, 8000s, 9000s — for the 'what did I leave running?' check before you close the laptop.
Catches unfamiliar processes
The menu bar icon turns orange when a command appears that isn't on your familiar list. Spot the rogue Electron app or background helper that started listening without you noticing.
Notices port changes
The icon flashes briefly when the port list changes (a server starts or stops). You'll notice when something starts listening, even with the popover closed.
Ignore list
Some processes always listen and you don't care — your VPN, Spotify, Ollama. Right-click to hide them from the list. Clear the ignore list any time from the footer.
Kill, force-kill, open
Click for SIGTERM, right-click for SIGKILL. Or open the URL in your browser, copy it, or reveal the working directory in Finder. No sudo needed for your own processes.
Free, MIT, no telemetry
Source on GitHub. Signed by GreenFlux, notarized by Apple = no Gatekeeper warning. No registration, no nag screen, no tracking.
Get it running in 30 seconds.
Three ways to install. Pick the one that fits your setup.
Download
Grab the latest release, unzip, drag to /Applications. Signed and notarized.
Homebrew
Already on Homebrew? Tap and install — one command.
brew install --cask greenflux/tap/port-watcherBuild from source
MIT licensed Swift 6. Requires Xcode 15+ and macOS 14+.
git clone github.com/greenflux/port-watcher
cd port-watcher
make installFor working-directory resolution, grant Full Disk Access in System Settings → Privacy & Security. Optional — everything else works without it.
Common questions.
Is it really free?
Yes. MIT licensed, source on GitHub. No subscription, no account, no upgrade tier, no nag screen.
Does it send any data anywhere?
No. There is no network code in Port Watcher. It reads local system state via lsof and ps and renders the result. That's the entire app.
Why does it ask for Full Disk Access?
To read the working directory of processes outside your shell session. macOS gates the lsof -d cwd lookup for arbitrary processes behind Full Disk Access. Without it, the app still works — you just see 'Unknown' for some processes' working directory.
Does it need my password to kill processes?
No. Port Watcher only shows processes owned by your user, and you can kill your own processes without sudo.
Will it slow down my Mac?
No. It runs a couple of lsof and ps invocations every 5 seconds — the same commands you'd run by hand. Idle CPU is effectively zero.
Apple Silicon, Intel, or both?
Both. Universal binary, macOS 14 (Sonoma) or later.
Will there ever be a paid version?
The GitHub build will always be free and MIT licensed. A paid App Store version may exist for convenience (auto-updates, easy install) — same app, your choice.