How can I tell which app is using data?

[JGG680]

I am seeing data usage spikes at times when I know I was not actively using my phone.  The web site shows me how much data is being used and when, but I want to know which app is doing this so I can kill it or uninstall it.

[rcschnoor]

This would certainly depend on the phone you are using.

[JGG680]

Android - Samsung Galaxy S4

[Ann154 · Accepted solution]

Settings > Data Usage to see the usage on the phone.