The idea of building good habits or breaking bad ones has become mainstream, with books like Atomic Habits and Tiny Habits arguing that small daily behaviors are more important than dramatic gestures. However, building new habits can be challenging, and tracking when you do them is crucial to success. A habit tracker app can help with this by allowing users to track their habits in a convenient and flexible way. The article reviews five of the best habit tracker apps for iPhone and Android users, including Streaks, HabitNow, Way of Life, Habitify, and Habitica. Each app has its unique features and pricing plans, but they all share the goal of helping users build lasting habits.