Have you ever wondered how people came up with one strong app idea, and turned their entrepreneurial dream true? As the use of mobile apps has become indispensable in our daily lives, several entrepreneurs have grabbed this opportunity and invested in developing a mobile app. With thousands of apps making millions and winning the heart of their users, you can too get your own app developed. If you have considered developing a mobile application, but not sure which app to go for, here are 21 best app ideas for your startup you must consider!