ShiftKing is a free iPhone app developed by JEONGGEON LEE that helps you keep track of your shift schedule. With ShiftKing, you can easily indicate your shift work on each day of the calendar and make notes or overwrite your shift if needed. The app also provides a table view of your shift schedule and offers a widget for quick access.

One of the standout features of ShiftKing is the ability to calculate annual leave, making it convenient for employees to plan their time off. Additionally, the app allows you to customize the color of your work elements and syncs with your iPhone's calendar to display public holidays.

For companies with non-periodic shift patterns, ShiftKing offers the option to create a shift schedule database, allowing colleagues to easily check their own schedules. This feature is particularly useful for workers in industries such as private bodyguard or nursing.

ShiftKing provides a simple and intuitive interface for managing your shift schedule, making it a valuable tool for anyone with shift work.