of apps. With AndroZoo, we aim to provide the software engineering research community with an unrestricted, scalable and up-to-date access to Android apps. To that end, we have developed specialised crawlers for several market places to automatically browse their content, find Android applications that could be retrieved for free, and download them into our repository. To the best of our knowledge, the total number of apps that we have collected constitutes the largest dataset of Android apps ever used in published Android research studies. Often, it is impossible to know beforehand how many apps are available in a given market. Therefore, some of the markets for which we wrote dedicated crawlers proved to be much smaller than initially expected. The crawlers we wrote follow two main objectives: a) Collect as many apps as possible, and b) Ensure the lowest possible impact on the market infrastructure. These two objectives increased the cost of writing such crawlers since for every market a manual analysis of the website has been performed in order to detect and filter out pages with different URL but with similar contents, for example, lists that can be sorted according to different criteria. Similarly, a unique identifier for every 