WESIS is an iPhone application developed by Hoppen Systems Applications GmbH. It falls under the Education & Reference category and is free to use. To access this app, one must be a student or teacher at Liebfrauenschule Köln and have a WESIS account.

This app simplifies the process of checking information on WESIS by eliminating the need to log in to the website or visit the substitute schedule manually. Users can receive all WESIS information directly on their iPhone or iPod Touch, including free periods, substitute schedules, and announcements. Once logged in, the substitute schedule is accessible whether online or offline.