The Shia Calendar app, "تقويم الشيعة," is a specialized application for Shia events and occasions on iPhones. It offers a unique way to view today's date in three different calendars - Hijri, Solar, and Gregorian. Users can also customize the monthly view, set the first day of the week, and mark holidays. The app allows seamless switching between the three calendar systems and displays today's events and occasions. It also features notifications for events, with the ability to set notification times and view the age difference with the current date.

The full version of the app provides detailed event information, displays events for all days, categorizes events by months and days, and offers smart search functionality for event titles and details. Users can save today's date and event titles in text or image format for sharing purposes. The app aims to gather a comprehensive collection of Shia events and occasions, with ongoing updates and user engagement encouraged for continuous improvement.