Period Countdown is a simple countdown app that provides you with accurate information on your phone's display. When it is installed, you will see the extension icon in your browser's bottom right corner. This icon will provide you with all the information you need about the upcoming periods and days, including the exact time remaining, as well as a number of upcoming classes that you can use for calculating more precise information.

In the settings menu, you will be able to adjust the time and date format, to enable or disable the "Show notifications" feature. You will also be able to add a countdown button to your home screen and set the default value for this button to count your minutes, hours, or days.