하루기출OX is a study tool that provides access to a wide range of previous exam questions that are relevant to Korean public officials exams. It covers a variety of subjects, including law, police administration, and Korean history. The app is free to use and available on Android.

The app offers various modes of studying, including Basic Study, Short-term Study, and Smart Study. Users can filter questions by exam type and year, and the app also offers a Search mode for quickly finding specific questions. Additionally, there is a Test mode that presents 20 random questions for users to test their knowledge. There is also an Infinite Challenge mode that allows users to keep practicing until they get the answer right.

The app also offers Text-to-Speech mode and the ability to save questions as PDFs for offline study. Users can also bookmark questions and exclude questions they already know the answers to. Finally, there is a Mission mode that rewards users with points for answering five or fifty questions a day.