Ask which Mac system monitor to install and you get pointed at one of two: Stats, the free open-source one everybody recommends, or iStat Menus, the paid one people have been running for a decade. The honest answer to “which?” is that they’re not really competing. They answer different questions. Here’s the specific version of that, including where my own app fits, and where it doesn’t.
Stats: free, broad, and one caveat
Stats (by exelban, MIT-licensed, north of 41,000 stars) covers CPU, GPU, memory, disk, network, battery, sensors, Bluetooth and a clock. It is genuinely good software given away for nothing, it looks at home in the menu bar, and for most people it is the correct first install.
The one caveat is worth knowing before you rely on it, and it’s the maintainer’s own words rather than my opinion. The README says fan control “is in legacy mode. It does not receive any updates or fixes.” If fans are the reason you’re shopping, that’s the sentence that matters. Its network module also reports aggregate throughput, how much is moving, rather than which app is moving it.
iStat Menus: the most complete one
iStat Menus (Bjango, now version 7) is the deepest thing in the category, and has been for years. Per-app bandwidth breakdowns, fan control with rules that respond to temperature and battery state, notifications, weather, time zones, battery history, combined menu bar modes. If a Mac exposes a number, it probably shows it, with more polish than anyone else.
It’s a one-time purchase (around $12 when I last looked, and included in Setapp), which for a tool you glance at fifty times a day is not a serious objection. If you want one app to cover everything and you’re willing to pay once, this is still the answer, and nothing below is an argument otherwise.
Where Readout fits, and where it doesn’t
I wrote Readout because I wanted three specific things, not because the category needed another dashboard. It’s free and notarized, and it is narrower than both apps above on purpose: there’s no weather, no clock or calendar, no battery history, no notification rules. If you want those, stop here; the other two are better buys.
What it does concentrate on:
| The question | What Readout does |
|---|---|
| Which app is using my network? | Per-app rates plus rolling five-minute totals, with anything over 50 MB up or 500 MB down flagged |
| What happens if the fan app crashes? | The privileged helper reverts to automatic within 15 seconds of losing contact; also on quit, crash, and at 95° |
| What does the monitor itself cost? | Published budgets, measured with CPU-time soaks, and sampling stops entirely while the display sleeps |
Picking
Roughly: iStat Menusif you want everything in one place and don’t mind paying for it. Statsif you want broad coverage for free and don’t need fan control to be actively maintained. Readout if the questions in that table are the ones you actually have, particularly the network one, which is the reason it exists.
All three sit in the same strip of menu bar, and all three are cheap to try. The useful move isn’t reading comparisons, this one included. It’s installing the one that matches the question you keep asking, and deleting it if it doesn’t answer it.