Emotional problems in children and adolescents are a major concern with negative impact for their future development as adults. For this reason, interventions are needed in order to better reach children and adolescents` needs in a way that suits their preferences and are of interest for them. We will briefly present four types of mobile apps that we developed and tested in several studies along with the research testing their efficacy. REThink is a therapeutic game with demonstrated results that is based on the ra- tional-emotive behavioral therapy (REBT), with seven levels built to train various emotional regulation skills. We investigated the reliability and validity of the REThink game’s evaluation modules, with regard to the assessment of emotion regulation abilities in chil- dren/adolescents. Also, we successfully implemented the REThink game for children and adolescents with clinical and subclinical levels of emotional disorders. The latter study investigated the REThink game as a standalone intervention for reduction of emotional symptoms in children and adolescents, and in combi- nation with an online Rational Parenting program that was implemented in the REThink EMOTIONS platform/ app. The program is available on web and mobile, and it includes recent advancements in unconditional youth acceptance, the transdiagnostic ABC model of the Rational Emotive and Cognitive-Behavioral Therapy, and schema therapy techniques into a personalized intervention in an interactive format. The REThink game has also been tested in combination with ecological momentary assessment (EMA) and intervention apps. MoodWheel is an app that uses experience sampling procedures for the assessment of current/previous emotional distress and positive emotions. PsyPills app is a self-help psycho-educational instrument intended to build stress resilience by using psychological pills. We tested the apps in combination with the main intervention, namely the REThink Game for reducing stress-reactivity in two conditions (rejection task and real-exam situation) for children and adolescents.