DatenZähler is a free Android app that helps T-Mobile, Congstar, 1&1, and other D1 network users track their data usage. The app displays the amount of data consumed as an updated widget on the home screen. It also works partially on the D2 Vodafone network. However, it does not work for O2/E-Plus, otelo, klarmobil, callmobile with D2 contract, CallYa, and Lidl since October 2019 due to the discontinuation of the Vodafone status page.

Unlike the built-in data usage indicator, DatenZähler determines data usage from the provider's status page, taking into account inclusive volume (e.g., Spotify), StreamOn (e.g., Netflix), international data roaming, and special offers (e.g., DayFlat unlimited). The app offers a chart diagram, customizable widget layout, notifications with several alarm options, data usage indicator in the status bar, consumption forecast in the Android info center, monthly usage history with Dropbox export, themes, and Dark Mode.