What's a well-designed iOS app that can help me keep track of important dates, especially recurring ones like birthdays or academic deadlines?

From an academic perspective, the 'Countdown' app presents a novel approach to an old problem: time management. I find the ability to track dates down to the second intellectually satisfying, particularly when anticipating deadlines. The function to repeat events annually, monthly, or weekly is pedagogically sound for keeping track of recurring commitments, such as assignment due dates for my students or my own research milestones. The app's customizability, allowing you to design countdowns for different events, is also a well-researched design. It’s not just about counting down; it's about visually organizing time, which can be incredibly beneficial. I haven't tested its cross-platform compatibility extensively, but it seems like a promising tool for anyone seeking to improve their temporal awareness.