OTO Vui is a free Android application developed by Yogroup Studio that helps you look up traffic violation fines in Ho Chi Minh City, Da Nang, Hanoi and other cities in Vietnam. The app is also being developed to include more features like automatic violation error reporting, information on traffic rules, and car news.

The app's main functions include a detailed lookup for traffic violation fines in Ho Chi Minh City and Da Nang, including images of the violation (if available). The app also allows users to check if their vehicle has any outstanding violations before registering it. Additionally, the app provides information on the contact details of the processing unit and allows users to look up their registration information. Finally, there is a daily error reporting function for vehicle owners. The app is constantly being updated and the developer is open to feedback.

Overall, OTO Vui is a useful tool for drivers in Vietnam, providing them with easily accessible information on traffic violations and other related information.