CPU · Memory · Battery · Network · Disk · GPU · Temperature · Fans
live in your menu bar — readable at a glance, and the bar never jumps around.
mectrics is a native macOS menu bar system monitor. Each module you enable draws a readable value — with a live sparkline where a trend actually tells you something — and stays out of the way otherwise. A click opens a detail popover with the numbers behind it. An optional Compact Health item collapses the whole machine into a single indicator that speaks up only when something needs attention.
It is built around three commitments:
| 🔒 Private by construction | Zero telemetry. No analytics, no identifiers, no crash reports. The only network request Mectrics ever makes is an update check, and it asks you once whether it may make that check on its own. The request carries nothing about you or your Mac, and an update is never installed without you. |
| 🪶 Light on the machine | About 27 MB of memory and a few percent of one CPU core while it sits in your menu bar — the same memory number Activity Monitor shows you. Sampling slows down on battery and backs off in Low Power Mode and when your Mac runs hot. |
| 📐 Stable in the menu bar | Items reserve a fixed width, so values change without anything shifting sideways. |
Those numbers come from half-hour runs of the shipping build, not from one glance at Activity Monitor, and they are checked before a release rather than assumed. What you see will differ with your Mac, how many items you put in the menu bar, and whether you are on battery — more items means more work, because each one redraws every second.
The project holds itself to deliberately tight internal budgets — 60 MB of memory and 3% of a core — and publishes where it stands against them rather than only the flattering half. Memory is comfortably inside; CPU currently sits just above. The measurements and the reasoning are written down, and so is how to run them yourself.
macOS 15+ · signed and notarized · 5.4 MB
Unavailable hardware hides itself — no Fans module on a fanless MacBook Air, no Battery on
a Mac mini. A missing reading shows a dash, never a fabricated 0.
| Module | What you can put in the menu bar | Sparkline |
|---|---|---|
| CPU | Usage %, per-core bars, temperature | ✅ |
| Memory | Usage %, used memory, temperature | ✅ |
| GPU | Utilization %, temperature | ✅ |
| Battery | Level with charge indicator, icon, health, cycles | — |
| Network | Stacked ↓/↑ activity, download only, upload only | — |
| Disk | Usage %, ring, used, free | — |
| Fans | Fastest fan RPM | — |
Sparklines are drawn for the three metrics where a trend is genuinely informative. The rest show a value, because a chart of your disk's fill level is decoration.
A module can contribute several independent items — Battery can show its icon and its health side by side. You pick components by clicking a live preview chip in the menu bar builder, so you choose from what you can actually see. Each popover adds the detail behind the value: per-core load and top processes for CPU, swap and pressure for Memory, hardware temperature for CPU, Memory, and GPU when the Mac reports it, read/write throughput for Disk, and so on.
CPU — a bar per core, and the top processes behind the disclosure |
Disk — capacity split three ways, plus live throughput |
- Compact Health — one status item that summarizes the whole machine and surfaces only what is off, including the two conditions macOS reports itself.
- Alert rules — sustained notifications with a live preview and test delivery, so you know what a rule will look like before it fires at 3am. Rules watch either a number you pick or a state macOS reports: your Mac slowing its CPU and GPU down to cool off, and the kernel's own memory pressure. A hot sensor is not the same thing as a machine that has actually been slowed, and memory can be nearly full with nothing wrong.
- Attention Log — a local, exportable record of what tripped and when.
- Energy Guard — sampling that steps down under Low Power Mode and thermal pressure.
- Menu bar builder — a visual layout editor with presets, where you toggle components by clicking their live preview instead of guessing from a list.
- Widgets — small / medium / large WidgetKit overviews for Notification Center.
- Diagnostics — a local-only system summary you can copy or export as plain text.
- Headless CLI — a read-only automation interface for alert events and one-shot health checks on Macs whose menu bar is not visible.
- Three-step onboarding, accent themes, and launch at login.
Compact Health — the whole machine in one item, quiet until it is not
Menu bar builder — click a live chip to add or remove it |
Alert rules — with the current reading next to each threshold |
Requires macOS 15 (Sequoia) or newer.
Download Mectrics.dmg from the latest release, open it, and drag Mectrics to Applications. The app is signed with a Developer ID and notarized by Apple, so it opens without a Gatekeeper detour.
Mectrics has no Dock icon and no window — after launching, look for it in the menu bar.
Updates are checked only when you ask, under Settings → General → Check for Updates….
The interface is available in English, Turkish, Russian, Spanish, French, and Brazilian Portuguese. Choose Settings → General → Language, then relaunch Mectrics when prompted.
The app bundle includes a read-only mectrics CLI for Macs whose menu bar is not visible.
The app remains the place where alert rules are configured. The CLI reads those rules and
exposes them to scripts and agents without changing any settings.
Choose Settings → Alerts → Install CLI… once to make mectrics available in every
Terminal. This creates a symbolic link at /usr/local/bin/mectrics; it does not download
another executable or install a background service. macOS may ask for administrator
permission.
Check the enabled rules without parsing output:
mectrics checkcheck exits with 0 when every current reading is within its limit, 1 when at least
one limit is crossed, and 2 when no rules are configured or the result cannot be
determined because a reading is unavailable. Add --json when details are needed:
mectrics check --jsonTake a one-shot snapshot of every available module:
mectrics snapshot --jsonThe snapshot includes each module's primary value, unit, timestamp, and detail fields; unsupported hardware is listed as unavailable rather than reported as zero. Stream actual alert activation and recovery events as newline-delimited JSON with:
mectrics alerts watch --jsonwatch does not print an initial snapshot. It waits quietly until a rule activates or
recovers, then writes that event to the Terminal as one JSON line. Use check --json when
the current state is needed immediately.
For a supervised, long-running stream, add a heartbeat interval:
mectrics alerts watch --json --heartbeat 60Heartbeat mode uses tagged NDJSON records. It writes a ready record immediately, periodic
heartbeat records, alert records for activation and recovery, and status records when
sampling coverage becomes degraded or recovers. Each heartbeat includes the latest sample
time and any unavailable conditions or stale metrics, so a consumer can distinguish a quiet
Mac from a live process whose sensor sampling has stopped. Without --heartbeat, the original
version 1 alert-event JSON remains unchanged.
A known crossed limit takes priority over an unavailable reading. check is immediate, so
a crossed limit means the corresponding sustained rule would enter its pending state now;
alerts watch remains the source for actual activation and recovery events.
JSON output goes to standard output. Startup information and errors go to standard error, so pipes stay machine-readable. The CLI samples only the metrics needed for the requested operation and makes no network requests. It does not include the app's live dashboard, settings, widgets, or history.
Invalid commands and flags exit with 64; corrupt saved configuration exits with 78; an
internal output failure exits with 70. These are separate from check's 0 / 1 / 2
health result. Run mectrics doctor (or mectrics doctor --json) to validate the executable,
saved rules, available alert coverage, installed command link, and current power source.
Run the CLI as the same macOS user who configured Mectrics. A root-owned cron job reads root's
preferences instead. Cron also commonly has a restricted PATH, so use
/usr/local/bin/mectrics check or set PATH explicitly. check is the command for cron and
other one-shot probes; alerts watch is a persistent stream and should be run under a process
supervisor rather than launched repeatedly by cron. A watch session takes a snapshot of the
enabled rules when it starts, so restart it after changing rules in the app.
Dragging Mectrics to the Trash removes the app but not its settings — macOS keeps those
for every app, which is why a reinstall goes straight back to your old layout instead of
showing onboarding again. For a clean removal, choose Settings → General → Uninstall….
Mectrics unregisters its login item, quits, then removes the app, its settings, alert rules,
Attention Log, caches, and its optional /usr/local/bin/mectrics link. macOS may ask for
administrator permission when that link is present.
macOS may retain the widget's protected cached snapshot after removal; it reclaims that container once the extension is gone. If Mectrics cannot be opened, use the manual uninstall script instead:
curl -fsSL -o /tmp/mectrics-uninstall.sh https://raw.githubusercontent.com/farukkamcici/mectrics/main/scripts/uninstall.sh
zsh /tmp/mectrics-uninstall.shIt lists what it will delete and asks before touching anything.
git clone https://github.com/farukkamcici/mectrics.git
cd mectrics
brew install xcodegen
xcodegen generate
open Mectrics.xcodeproj # then ⌘RFull setup notes, including code signing, are in CONTRIBUTING.md.
Zero telemetry — not "anonymized", not "opt-out". No usage data, hardware information, metric history, or alert configuration ever leaves the device. Every number comes from a local, read-only system interface.
The single network request the app can make is an update check, and only when you choose
Check for Updates…. Read the full statement in PRIVACY.md.
Knowing what a project will not do is what keeps it small enough to trust. Mectrics reads the machine it runs on and reports what it finds. Everything below is out of scope, and an issue asking for one of them will be closed with a link here rather than a debate.
- Telemetry of any kind, including anonymous, aggregated, or opt-in. There is no version of this that gets built.
- Accounts, cloud sync, or a companion service. Nothing here needs a server, so nothing here will grow one.
- Anything outside the machine. Remote hosts, SaaS quotas, API usage, container fleets: all reasonable things to monitor, none of them this app's job.
- Acting on what it finds. Mectrics does not kill processes, purge caches, or change system settings. It shows you the number and hands you off to the tool that owns the action, which is why the popovers open Activity Monitor and System Settings instead of reimplementing them.
- Benchmarking or stress testing. Reading a load is not the same as creating one.
- Other platforms. macOS only. No iOS companion, no Linux port.
- A window. The menu bar is the interface. There is no Dock icon and no main window, and that is a design decision rather than a missing feature.
Forks are welcome to disagree with every line of this. That is what the MIT license is for.
Contributions are welcome — new hardware coverage and translations especially.
If Mectrics is useful to you, you can support its ongoing development through GitHub Sponsors.
CONTRIBUTING.md— setup, the development loop, how to add a metric provider or a translationAGENTS.md— the conventions this repository enforces, and the source of truth for themdocs/architecture.md— how the app and the metric engine fit together, and where each number comes from
The translation workflow is documented in CONTRIBUTING.md.
Found a vulnerability? Please report it privately — see SECURITY.md.
Prior art that set the bar: Stats for proving an open source monitor can be excellent, and iStat Menus for the depth people expect. Built with Sparkle for updates and XcodeGen for a reviewable project file.
MIT © Faruk Kamçıcı