With most cellular carriers moving away from the beloved unlimited data plans of yore, many smartphone users now find themselves trying to cut back on data usage while still doing all of the things they want or need to get done on their phones. Unfortunately, that’s sometimes harder than it sounds. Some apps may seem simple enough, but could actually be downloading massive amounts of data in the background. Users could also be using an app much more than they realize, resulting in overages, fees, and a strong feeling of contempt for carriers.

Until now, there has been no way for iPhone users to track down which apps on their phones were using large chunks of their data plan without their knowledge. Fortunately, the good folks at Onavo have heard the cries of outraged users on limited data plans and come to our rescue.

Onavo Count, a new app from the creators of the data-compression app Onavo Extend, allows users to monitor how much of their cellular data plan each app or built-in service on their phone has used.

In my experience with the app, I’ve found that the counters are mostly accurate, although it does seem they only update a few times every day.

The interface is straight-forward and shows you everything you need to know at a glance. The color-coded graphs make data visualization easy, and you can even see how much data you have saved by using the free Onavo Extend app to compress the data sent over the cellular network.

Overall, Onavo Count is an incredibly useful tool for users with limited data plans who need to budget their megabytes more efficiently, or for anyone curious about how they use their phone.

Onvao Count is available on the App Store for free. Yes, this entire service is free.