Mac OS X already comes with a solid system monitor, but it’s not that great to just glance at your overall system health. For that, we like Monity, which sits in your Notification Center for easy access to a wealth of information.
Platform: Mac OS X
Monity’s real appeal is the fact it manages to hit the Goldilocks zone of system monitors. It’s lightweight and cheap, offers a solid amount of monitoring data, and doesn’t overwhelm you with options. The fact it’s in your Notification Center (as opposed to the menubar, like many other options), means it’s out of your way unless you really need it. It also means you can easily pull it up with a keyboard shortcut. Really, Monity’s main appeal is the fact it packs a lot of information into a small space without being too intrusive. If you’re really just looking for a simple system monitor that stays out of the way, Monity works perfectly.
Monity doesn’t have a ton of options and if you’re more interested in graphs instead of stats, you’re out of luck with Monity. The only way it displays data is with numbers, so while the design is certainly acceptable, it’s nothing to write home about it. Similarly, you can’t customize the data you see on a very granular level, so if you’re only interested in monitoring specific processes, Monity will fall short for you. Likewise, it’s missing temperature data. Monity only works in the Notification Center, so if that’s not something you’re interested in, then you’ll want to take a look at other options.
Activity Monitor, the utility that comes with Mac OS X, is a pretty solid system statistics monitor. You can see CPU, memory, network, and disk activity/usage, plus it breaks down everything by task. You can (force) quit tasks as needed, investigate what they’re doing, and organize them however you want. For the most part, Activity Monitor will be enough for most users so it’ll do the job just fine if you don’t need to constantly monitor your system activity.
If you’re looking for a seriously powerful, customizable, and tweakable system monitor, iStat Menus 5 ($16) is exactly what you need. It sits in the menubar, has a ton of dropdown menus, monitors everything you can possibly think to monitor, and even has app-specific statistics. It’s extremely powerful, but isn’t really necessary for the average user. If that’s too much for you, iStat Mini ($2.99) works similarly to Monity by sitting in your Notification Center, but doesn’t have quite the same amount of data.
MenuMeters was our previous pick here and it’s still a solid system monitor if you don’t mind the fact it takes up a ton of space in your menubar. It can do everything Monity can do and more, with custom display options and a ton of different meters. It’s a bit on the ugly side, but it’s also free and open source.