For my PhD studies I followed the method of research through the app store. Some of my apps are still available on the Google Play Store. You’ll find them following the links below.


We believe that we can fundamentally improve phone calls on smartphones. Ever been interruption from an app through a call? CallHeads will give you more control on what to do with a phone call when you are concurrently using an app. Instead of a fullscreen notification popping up and interrupting your app, you will see a bubble as an overlay on your app, and you can keep using the app. For instance, if you are currently reading a text, you can first finish the current paragraph until you pickup the call, if you are playing Angry Birds, you can first finish the slingshot and then answer the phone. I have used CallHeads for studying new ways for notifying users of incoming calls.


AppDetox helps you to calm down your mobile app usage, and take a digital detox. You are able to set your own rules for your app usage to detox from some heavy app usage and stop procrastinating. According to your own rules the use of some apps will be forbidden. You will see temptations when you tried to launch an app against your rules in a log. We have leveraged AppDetox to study people’s addictions to apps.


AppKicker was one of the fist adaptive app launch menus available for Android devices. AppKicker provides quick-start icons for the apps you most likely launch next. The list is automagically updated while you use your apps or games. The widget is triggered when you use an app and it always shows you up to five apps to launch them next. When you have a gaming session, you can easily come back to your recent games, when you are in the office you can easily come back to your recent productivity tools. You can simply tap on the apps’ icons presented by the widget. No need to maintain different desktop pages for that any more. You will have more space on your home screen for other widgets. Our app is an always up-to-date quickstart launcher. I have used AppKicker to study how we can build adaptive mobile menus.


How fast can you find your app icons? Who can start her apps fastest? Who knows best where his apps are located? Are you fast finding icons in your launcher? Try to beat your buddies on rappidly! rappidly is a race game for apps. Compete against your friends and post your records to Facebook. I have used rappidly to study how fast people can find icons within their app menus.


appazaar was one of the first context-aware mobile app recommender systems available for the Android app store. I started working on it in 2007 — in fact before the first mobile app stores came up. We took the app offline, but you’ll find some information here.