תפילון - סידור חכם is a free iPhone app that provides users with a comprehensive prayer book. The app shows the correct prayer for each day, including special prayers for holidays such as Hanukkah and Purim. One of the standout features of this app is that it does not require an internet connection to access the prayers. All calculations of times and dates are done within the device itself.

The app offers various customization options, allowing users to choose which additional prayers to display and when to celebrate Purim. It also provides the ability to view the day's times in 120 cities around the world. The app supports different prayer traditions, including Ashkenazi, Sephardic, and Yemenite.

With its extensive collection of prayers, customizable features, and offline accessibility, תפילון - סידור חכם is a valuable tool for those looking to enhance their prayer experience on their iPhone.