Peer feedback can be described as the act of one learner evaluating the performance of another learner. It has been shown to impact student learning and achievement in language learning contexts positively. It is a skill that can be trained, and there have been calls for research on peer feedback training. Mobile microlearning is a type of technology-enhanced learning which is notable for its short duration and flexibility in the time and place of learning. This study aims to evaluate how an asynchronous microlearning app might improve students’ skills for providing peer feedback on spoken content in the context of English as a foreign language (EFL) education. This study used convenience sampling and a quasi-experimental single-group pre-/post- research design. Japanese university students ( n = 87) in an EFL course used the Pebasco asynchronous microlearning app to practice peer feedback skills. The students’ app usage data were used to identify five behavioral profiles. The pattern of profile migration over the course of using Pebasco indicates that many participants improved or maintained desirable patterns of behavior and outcomes, suggesting a positive impact on the quality of peer feedback skills and second-language (L2) skills, as well as the ability to detect L2 errors. The findings also suggest improvements that can be made in future design iterations. This research is novel because of a current lack of research on the use of no-code technology to develop educational apps, particularly in the context of microlearning for improving peer feedback skills in EFL.