DataMan Next is the simplest app to use if you want to avoid extra charges for data service to your phone or tablet. Made for iOS devices, it tracks data usage against your service plan’s monthly or weekly allowance. Open the app and you’ll instantly see the percentage of data left on the plan and whether you’re on pace to stay under your limit. ($2)
My Data Manager is like DataMan, but works for Android or iOS. The display “is a bit more fussy” than its elegant counterpart, but it’s free “and provides a more thorough measure of data habits.”
Onavo Count performs similarly to the previous two apps. A “minimalist interface and intuitive graphs” track usage while offering the handy bonus of breaking down what’s eating up data, be it watching videos or social media usage. (Free, Android or iOS)
Source: The New York Times