Many studies about digital wellbeing and related tools mainly focus on the interaction between the user and a single device. In the modern multi-device world, the definitions of digital “habit”, “overuse”, “addiction” look reductive if uniquely related to the smartphone. Nowadays, people deal with more than one type of device, e.g. smartphone, PC, tablet, smartwatch, smart TV and often use them in a concurrent way, thus motivating the need for exploring digital wellbeing in a multi-device setting.

In this thesis, I analysed the literature referred to digital wellbeing, searching for some studies that include multi-device and cross-device environments, with the aim to define in a rigorous way the concept of multi-device digital habit, and the self-control strategies that can be adopted in a multi-device environment.
Afterwards, I present a prototype of multi-device tool, “FeelHabits”, built with for improving those digital habits that involve both the PC and the smartphone. The thesis presents the results of a test of the tool, conducted on a small number of users, evaluating the effectiveness of the built system and assessing the future potentiality of designing multi-device Digital Self Control Tools.