DEV Community: Le Thanh Viet

I built a free, open-source system monitor for the macOS menu bar

Le Thanh Viet — Fri, 02 Oct 2026 18:05:07 +0000

TL;DR

MoniMac is a free, open-source system monitor for macOS. It keeps CPU, memory, GPU, network and temperature one glance away in your menu bar, and tells you the moment an app starts dragging your Mac down. It's a native Swift app, under 10 MB, with no account, no analytics and no paid tier.

🌐 Website: https://moni-mac.vercel.app/
💻 Source: https://github.com/lethanhvietctt5/moni-mac
⬇️ Download: https://github.com/lethanhvietctt5/moni-mac/releases/latest/download/MoniMac.dmg

What it does

A menu bar that adapts to you

Each metric (CPU, memory, network, GPU, temperature) can live in the menu bar as its own item, in one of three styles:

Value only: compact numbers
Graph only: a 60-second sparkline
Value + graph: the most information, the most width

When a metric runs hot, its item turns into a warning sign. Hover to see the cause, click to find the app behind it. Hold ⌘ and drag to reorder items, or drag one off the bar to hide it.

One click, the whole picture

Click any item and a popover shows every metric at once, plus the apps working hardest right now. Tabs take you to CPU, memory, GPU, network, disk and battery, with live history, per-core load (P and E cores) and the top apps.

Every number, broken down by app

CPU, memory, GPU, network, disk and power for each app, with helper processes grouped under the app they belong to. That last part matters more than it sounds: a browser or Electron app is dozens of processes, and a flat list hides the real culprit.

Alerts based on patterns, not spikes

A single busy second isn't a problem, so MoniMac waits until a pattern holds:

CPU: one app stays above your threshold for 2 minutes
Memory: an app grows fast (+1 GB in 10 minutes may be a leak)
Disk: sustained heavy writes
Network: heavy uploads running in the background

And the fix is one click away. The quit sheet lists the app and every helper process with their CPU and memory, then asks apps to quit normally so you can save your work.

Beyond CPU and RAM

Battery: charge, health, cycle count, live power draw, and which apps drain it
Bluetooth: AirPods left/right/case, keyboard, trackpad and mouse levels
Sound: per-app volume, so you can mute the one that keeps chiming
Temperature & fans: read-only sensor temperatures and fan speeds

For developers: Projects

This one is for the "that dev server from last week is still running" problem. Projects finds every local dev server (Next.js, Vite, Docker, FastAPI and more), groups them by repo, shows port, uptime and memory, flags the ones idle for days, and lets you stop them in one click.

How it compares

	Activity Monitor	iStat Menus	MoniMac
Live metrics in menu bar	❌	✅	✅
Price	Free	Paid	Free
Open source	❌	❌	✅
History	❌	✅	✅ [30 / 90 days, see note]
Alerts when an app misbehaves	❌	✅ [verify]	✅
Local dev server finder	❌	❌	✅

[Verify the iStat Menus cells before publishing, or delete the table and describe the difference in one paragraph. Stats is another free open-source alternative worth mentioning respectfully.]

Install

Requirements: Apple silicon (M1 or later) and macOS 14.2+. Intel Macs aren't supported.

Download MoniMac.dmg from Releases.
Drag MoniMac into Applications.
MoniMac isn't notarized by Apple yet, so macOS blocks it until you remove the quarantine flag. Run this once in Terminal:

xattr -dr com.apple.quarantine /Applications/MoniMac.app

Updates install from inside the app.

Contributing & feedback

MoniMac is at v0.1.1, so it's early and feedback matters. Issues, ideas and PRs are welcome: https://github.com/lethanhvietctt5/moni-mac

What would you want a menu bar monitor to tell you that Activity Monitor doesn't? Let me know in the comments 👇

I built an open-source, free alternative to CleanShotX

Le Thanh Viet — Fri, 02 Oct 2026 17:56:21 +0000

TL;DR

I built Lightshot, a free and open-source app for macOS that captures, annotates and records your screen, with a video editor built in. Everything runs on your Mac: no account, no cloud, no uploads.

🌐 Website: https://lightshot-mac.vercel.app
💻 Source: https://github.com/lethanhvietctt5/lightshot

What it does

Capture: grab a region, window or full screen.
Annotate: mark up screenshots right after capturing to point at what matters.
Record: record your screen when a still image isn't enough.
Edit video: trim and polish recordings in a built-in editor, without opening another app.
Local-only: your files stay on your machine. No account, no telemetry, no uploads.

Install

Download the latest .dmg from Releases.
Drag the app to Applications.
On first launch, grant Screen Recording permission in System Settings -> Privacy & Security.

Contributing & feedback

It's fully open source, so issues, ideas and PRs are welcome: https://github.com/lethanhvietctt5/lightshot

What's the one feature you'd want in a screenshot tool? Tell me in the comments 👇

Clone Spotify ReactJS

Le Thanh Viet — Fri, 02 Jul 2021 14:22:35 +0000

I have complete cloning Spotify using ReactJS and NextJS
Here is my source and I hope it will help everyone who is learning React and want to clone Spotify
Video demo: https://youtu.be/REwB-8QaHLc
Github: https://github.com/lethanhvietctt5/react-spotify
Facebook: https://www.facebook.com/thanhviet.le.ctt5/
Email: lethanhviet7c@gmail.com

ReactJS, Socket video chat app

Le Thanh Viet — Fri, 02 Jul 2021 04:55:41 +0000

I have complete my video call and chat real-time app by using ReacJS, Socket.IO, PeerJS. I want to share it with everyone who is learning React and Socket.
Link: https://room-call-chat-app.herokuapp.com
Github: https://github.com/lethanhvietctt5/video-chat-app
Facebook: https://www.facebook.com/thanhviet.le.ctt5/
Email: lethanhviet7c@gmail.com