Vocabulary is one of the building blocks of second language learning which is essential for acquiring various aspects of language (i.e., communication skills, listening/reading comprehension, and writing). WordUp is an artificial intelligence application for learning new English words, appropriate for all levels of proficiency and even for native speakers. This systematic review, by synthesizing the results of relevant research studies, examines the effect of the WordUp application on L2 learners’ vocabulary development. Based on predefined inclusion criteria and quality assessment and through an extensive review of databases, relevant studies were identified and screened for inclusion. The studies were carefully evaluated to provide comprehensive insight into the potential strengths and weaknesses of this application for vocabulary development. Moreover, a semi-structured interview was conducted with 20 participants with predefined guiding questions with a focus on elaboration on certain issues such as graphics, user-friendliness, ease of installing the program for various devices, ease of use of the program, and strengths and weaknesses. This study aims to provide a dedicated understanding of how WordUp contributes to vocabulary development and provides valuable implications for researchers, educators, and EFL learners to optimize their vocabulary instruction by using word processor tools like WordUp. The result showed that despite all the weaknesses, this application has a significant effect on vocabulary development. This study may hopefully help to enhance the effectiveness of WordUp in promoting learners' vocabulary development.
