Dua is the one of highest forms of worship. There is nothing more beloved to Allah than the supplication of his slave.
Demo: https://codecanyon.net/item/islamic-dua-hijri-calendar-hijri-islamic-calendar-ythe-islamic-calendar-muslim-apps/48655693
Muslim Pro is an Android app that provides all Muslim needs, Holy Quran without servers and no extra space, Azkar and Duaa, and also contains a reminder reminds you of a specific time.
Demo: https://codecanyon.net/item/muslim-pro-holy-quran-duaa-reminder/28833529