Vocabulary is one of the most important things in English language learning. Improving vocabulary is quite challenging for many students since English is a foreign language in Indonesia. Improving students’ vocabulary needs various strategies, such as using Plickers. Plickers is a web-based formative assessment tool suitable for low-tech classrooms. It requires two devices: a desktop computer and a smartphone to running the Plickers app. The purpose of this study was to determine how students’ perceptions of the impact of using Plickers to improve their English vocabulary and the challenges of using them This study was conducted at SMPN 1 Blangpidie, involving six classes of the first year as the population. In selecting the sample, the researcher selected VII B with 30 students as the sample. This research used questionnaires for data collection. The questionnaire is composed of 14 questions: 13 Likert-scale questions and 1 open-ended question. The study shows that the students perceived that Plickers has a significant impact on improving their English vocabulary. Besides, the students felt highly motivated and highly interested in improving their English vocabulary. Nonetheless, students sometimes forgot to recheck their cards and sometimes experienced weak internet connections.