Collecting personal user data helps software developers to improve the product. However, it must be conducted in an consensual and transparent manner. In this paper, we compared several approaches to collecting personal data from users in the context of an informal e-learning system. More specifically, we asked the learners to donate their personal data by a filling an optional questionnaire and explicitly stated how the data will be used by the developer. We designed and implemented an open-source package for gathering the data, and highlighted some of the ethical and technical aspects. We then experimented with several alternative settings for the questionnaire to optimize the consent rate. We conclude that our approach to data collection can be an effective supplement to existing data collection practices.