In the context of adolescents’ increasing engagement with digital media, accurately assessing their media usage becomes challenging. This complexity arises from factors such as heightened multitasking, shorter attention spans, and peer influence. The Mobile Experience Sampling (MES) method has emerged as an alternative in digital media research with the strong advantage of measuring media use in situ several times a day over an extensive period. However, there is a lack of research investigating how MES studies among teenagers should be set up and which specific MES tools should be used to ensure high response rates. To answer this question, we conducted a multi-method study (N = 34) comparing data quality indicators (i.e., response rate and response delay) and perceived usability of a web-based and an app-based MES tool among Austrian middle and high school students, consisting of a one-week experimental MES study followed by qualitative interviews. In the MES part, participants were notified by three beeps on three days (NMES = 306) to complete a short survey measuring their time use in the last 60 minutes. The qualitative interviews revealed that adolescents perceived both MES tools as positive regarding usability (except for installation). The MES data, however, show great differences in data quality, highlighting that the web mode generated higher response rates and fewer errors (e.g., for response delays due to technical problems) than the app mode. This study provides a deeper understanding of technological considerations that should be made when planning an MES study and offers methodological guidance for future research.