<![CDATA[Self-directed vocabulary learning has become increasingly relevant in digital language learning environments, particularly as mobile applications provide learners with flexible opportunities to practice English beyond formal classroom settings. Duolingo offers a gamified learning environment that enables learners to engage in vocabulary practice through short lessons, immediate feedback, progress tracking, and motivational features. This study aims to explore students’ self-directed English vocabulary learning through Duolingo by examining the strategies they employ, the factors that motivate their learning, and the ways they maintain learning consistency. This research employed a qualitative approach with a case study design involving five junior high school students from MTsN 1 Kediri who actively used Duolingo for independent English vocabulary learning. Data were collected through open-ended questionnaire worksheets, non-participant observation, and documentation of students’ Duolingo learning activities. The data were analyzed using the interactive model of Miles, Huberman, and Saldaña, consisting of data condensation, data display, and conclusion drawing and verification. The findings reveal that students developed self-directed vocabulary learning routines by integrating Duolingo into their leisure time and employing various strategies, including translation, note-taking, contextual guessing, and pronunciation practice. Students’ learning motivation was supported by personal goals, gamified features, progress tracking, and peer competition. The findings also indicate that the daily streak feature played a particularly important role in maintaining students’ learning consistency, while social support and technical conditions influenced their learning experiences. Despite these motivating factors, students encountered obstacles including unstable internet connections, device limitations, application bugs, and the heart/energy system. Overall, Duolingo provided a flexible digital environment that supported students’ autonomous vocabulary learning by combining self-directed strategies, motivational mechanisms, and routine-based learning practices.]]>
