Port Monitor

A small macOS menu bar app that shows which local ports are listening, which process owns them, and lets you kill that process without leaving the menu bar.

Download · What it does · Build from source · Usage

Why port monitor

Port Monitor is for the familiar "what is using this port?" moment. Click the menu bar icon, see the current TCP listeners, and stop the one you do not need anymore.

What it does

• Shows active listening TCP ports
• Lists the process name and PID for each port
• Lets you kill a process right from the menu
• Runs as a menu-bar-only app, so it stays out of the Dock
• Ships as a universal build for Apple Silicon and Intel Macs

Download

1. Open the releases page.
2. Download PortMonitor.dmg from the release assets.
3. Open the DMG and drag Port Monitor into Applications.
4. Launch the app from Applications.

Note

Port Monitor currently targets macOS 26 or later.

Important

Release builds are convenience builds for now. The app is not signed or notarized yet, so macOS Gatekeeper may warn on first launch. If that happens, open the app from Finder with Open, or build it locally.

Build from source

Requirements

• macOS 26+
• Xcode 26 or Apple developer tools with Swift 6.2+
• iconutil (included with macOS)

Build commands

# Run tests
swift test --build-path /tmp/portmonitor-spm --disable-experimental-prebuilts -j 2

# Build the app bundle
./scripts/build.sh

# Package a DMG
./scripts/create-dmg.sh

Artifacts end up in build/:

• build/PortMonitor.app
• build/PortMonitor.dmg

Release process

• Pushes to main and pull requests to main run CI, test the app, build the app bundle, package the DMG, and upload both as workflow artifacts.
• Pushing a version tag like v1.0.1 publishes a GitHub release and attaches PortMonitor.dmg automatically.

How it works

Port Monitor uses lsof -nP -iTCP -sTCP:LISTEN -FpcnT to find local listening TCP ports. It parses that output, turns it into app models, and shows the results in a menu bar UI. From there you can refresh the list, see which process owns a port, and kill it when you need to free something up.

Usage

1. Launch Port Monitor.
2. Click the menu bar icon.
3. Review the current listening ports.
4. Click Kill next to a process you want to stop.
5. Use the power button to quit the app.

Project layout

PortMonitor/
├── PortMonitor/              # App entry point, UI, services, models
├── Tests/PortMonitorTests/   # Parsing, command runner, view model tests
├── scripts/                  # Build, packaging, and icon tooling
├── assets/icons/             # Source artwork and exported icons
├── Package.swift             # Swift Package Manager setup
└── project.yml               # XcodeGen project definition

Development notes

• The app is a menu-bar-only macOS app via LSUIElement.
• CI validates pushes and pull requests, and release automation publishes a DMG from GitHub Actions when a v* tag is pushed.
• The packaged app is built as a universal binary for Apple Silicon and Intel Macs.