Vocabulary mastery is an important aspect for language learners. In order to make vocabulary learning become more advance and effective, a website called vocabulary.com is created. Vocabulary.com facilitates the users to learn vocabulary in more interesting ways through the website’s features. This research aimed to find out the students’ perceptions on the benefits and also the challenges of learning vocabulary through vocabulary.com. The research applied qualitative research approach. The research took place in English Language Education Department of Muhammadiyah University of Yogyakarta. There were four participants in the research, consist of three females and one male. They are active ELED’s students from batch 2015 who still use the website until this research was conducted. In order to collect the data, the researcher conducted interviews. The findings were taken from the interview result which had been coded and analyzed. The findings show that there are four benefits and also five challenges of using vocabulary.com. The benefits are enriching new vocabularies, knowing how to construct daily life sentences, storing vocabularies in long-term memory, and establishing self-regulated learning. The challenges are lack of internet connection, lack of technology skill, cheating, distraction from other applications, and also no guidance from the teacher.