I have been puzzled with my high monthly data usage, and the stock Android “Data Usage” summary does not appear to be accurate. After installing this app, I finally realise which apps are the culprit and what time they are consuming data. The app breaks down my data usage based on apps, by the hour, day, and month, filtered by connection type (Mobile, WiFi, Roaming). To manage your monthly usage, you can configure your data plan so that the app displays your remaining data quota and remaining days from the pulldown notification panel.
How do I know the app is accurate? I compared the app statistics to the data usage details from my mobile service provider app, My StarHub.