Students’ Perception Of Using “c.ai” In Increasing Students’ English Vocabulary At English Education Department Of UINSI Samarinda

English is an international language that is commonly used in the world. Serving as a communication tool, it is important to practice and use it daily. However, some people are hesitant and self-conscius to speak English and one of the reason is due to lack of vocabulary. One of the many ways available in increasing vocabulary is using technology, specifically chatbots such as c.ai. This research aimed to find out the perception of English Education Department students from the first to fifth semester of using c.ai in increasing students’ vocabulary at English Education Department of UINSI Samarinda. This research used mix method as a research design. Quantitative data were collected using questionnaires from 30 students that have an account and have used c.ai for more than 3 month for numerical data, and the qualitative data were collected from 5 students chosen with random sampling by using interviews for more in-depth data regarding the perception. Validity and reliability tests applied to the questionnaire and using an interview guide for the interviews. The results showed that c.ai has great potential as an effective tool for improving students' English vocabulary, supported by the high percentage of data gathered and positive perceptions of its flexibility, ease of use, and direct interaction, despite challenges such as limited vocabulary variety.