MenuBarMonitor

A tiny native macOS menu bar app for CPU and memory usage.

C 18% M 62% in your menu bar. No Dock icon, no charts, no background noise.

Download DMG · Latest release · Report an issue · Star the repo

Why

MenuBarMonitor is built for people who want Activity Monitor-level awareness without opening Activity Monitor.

• Glanceable: CPU and memory are always visible in the macOS menu bar.
• Native: built with Swift and AppKit, no Electron runtime.
• Quiet: no Dock icon, no notifications, no history tracking.
• Lightweight: 2-second refresh by default, optional 5-second low-power mode.
• Practical: optional launch-at-login support.

If this saves you a trip to Activity Monitor, consider starring the repo.

Screenshots

MenuBarMonitor keeps CPU and memory visible in the macOS menu bar:

Click it to see details and quick controls:

Compatibility

• macOS 13 or later.
• Apple Silicon Macs for the current GitHub release.

This means M1, M2, M3, M4, and newer Apple Silicon Macs. Intel Mac support is not packaged yet. The current DMG is built as arm64.

Install

1. Download MenuBarMonitor-v0.1.0-macOS-arm64.dmg.
2. Open the DMG.
3. Drag MenuBarMonitor.app to Applications.
4. Open MenuBarMonitor from Applications.

The app appears in the menu bar as C ... M .... It does not show a normal Dock icon.

Do not download Source code unless you want to build the app yourself.

First Launch Notice

The current GitHub build is ad-hoc signed and not notarized yet. On first launch, macOS may block it.

If that happens, right-click MenuBarMonitor.app, choose Open, then click Open again. This is only required once.

If macOS still blocks the app, open System Settings > Privacy & Security and choose Open Anyway.

Usage

Click the menu bar text to open the menu.

Available actions:

• View CPU and memory details.
• Switch between normal refresh and low-power refresh.
• Toggle launch at login.
• Quit the app.

Privacy

MenuBarMonitor does not use analytics, does not connect to the network, and does not send data off your Mac. It only reads local system CPU and memory statistics.

Development

Requirements:

• macOS 13 or later.
• Xcode Command Line Tools with Swift.

Run from source:

./scripts/run-app.sh

Run checks:

./scripts/run-tests.sh
swift build

Package the app:

VERSION=0.1.0 BUILD_NUMBER=1 ./scripts/package-app.sh

Package the DMG:

VERSION=0.1.0 BUILD_NUMBER=1 ./scripts/package-dmg.sh

The DMG script creates:

dist/MenuBarMonitor-v0.1.0-macOS-arm64.dmg
dist/MenuBarMonitor-v0.1.0-macOS-arm64.dmg.sha256

For public distribution beyond GitHub test releases, use a Developer ID Application certificate and notarize the result:

CODE_SIGN_IDENTITY="Developer ID Application: Your Name (TEAMID)" \
VERSION=0.1.0 BUILD_NUMBER=1 ./scripts/package-dmg.sh

App Icon

The packaged app icon is generated from Assets/AppIcon.png during macOS packaging.

To replace it later, replace Assets/AppIcon.png with another square PNG and run the packaging script again.

Performance Notes

MenuBarMonitor is intentionally small:

• It samples every 2 seconds in normal mode.
• It samples every 5 seconds in low-power mode.
• Sampling runs away from the menu bar UI thread.
• It does not store history or draw charts.

For a manual check, open Activity Monitor and verify the app does not show sustained CPU usage while idle.

License

MIT License. See LICENSE.