21st-century language learning involves technology as a medium of learning. Over the centuries, various technologies have been created to synchronize the language learning process to the present-day phenomenon that results in flexibility - students can learn a language anywhere, anytime even without a teacher. As the newest information technology, smartphones have now functioned as mini-computers that are used by students for language learning.  It promotes autonomous learning, that is the ability to control one’s learning and the potential ability to act in learning situations.  This research aims to investigate the potential of smartphones in promoting autonomous language learning, focusing on three questions; (1) what smartphone applications are used by students for language learning, (2) what skills are associated with it, and (3) how they use them for language learning. An interview and smartphone log were used to collect the data. The findings showed that there are 51 applications used by the participants. Those applications are used for different purposes in language learning.