<p>Personal data collection in web applications should follow mandated legislative frameworks such as the EU General Data Protection Regulation (GDPR) principles. Among others, web data collection forms should provide clear and transparent explanations regarding the purposes of the collection. At the same time, for users’ ease, such forms should follow standard usability principles. There have been works studying the merging of usability principles and privacy standards. Building on this line of work, we exploit the usable privacy heuristics, in combination with a set of relevant GDPR principles and the current website landscape, to create a user-centred design for transparent, usable, and GDPR-aware web forms through high-fidelity prototypes. We developed and validated a purposes dataset, both in human-readable and machine-readable formats. Finally, we developed a tool to assist web engineers in creating such forms and integrating them into their websites. We present an evaluation of the tool, demonstrating overall positive results and highlighting the potential of our approach to improve transparency at the point of data collection.</p>