A qualitative short-term longitudinal study was conducted, using a sample of 29 smokers allocated to one of the 2apps, Quit Genius or Smokefree. Each user underwent 2 one-to-one semistructured interviews, 1 week apart. Thematic analysiswas carried out, and important themes were identified. Descriptive statistics regarding participants’ perceptions and health behaviorin relation to smoking cessation are also provided.The thematic analysis resulted in five higher themes and several subthemes. Participants were generally more positiveabout Quit Genius’s features, as well as about its design and information engagement and quality. Quit Genius users reportedincreased motivation to quit smoking, as well as greater willingness to continue using their allocated app after 1 week. Moreover,these participants demonstrated preliminary changes in their smoking behavior, although this was in the context of our limitedsample, not yet allowing for the finding to be generalizable.