Microsoft officials have been saying for a couple of years that the company eventually planned to "retire" the Wunderlist app it bought in 2015 when it acquired 6Wunderkinder. Until today, December 9, Microsoft had not disclosed the Wunderlist retirement date. But now we know that on May 6, 2020, Wunderlist will be no more.
Microsoft is replacing Wunderlist with its To Do application, which it describes as its "one integrated and secure notetaking app." Microsoft's To Do app actually is one of several different task-management applications and services Microsoft currently offers. Others include Outlook Tasks, OneNote, Sticky Notes, Notepad, and Planner.
Microsoft already had stopped releasing new features and major updates to Wunderlist. As of today, December 9, Microsoft is no longer accepting new sign-ups for Wunderlist, even though the app will be supported until May 6, 2020. After that date, Wunderlist to-dos will no longer sync, though users will still have some time to import their lists into To Do.
Microsoft is making available an exporter tool (at export.wunderlist.com) to save their lists, tasks, subtasks, files, comments and notes as a .zip file. Microsoft also has an importer to move Wunderlist lists and tasks to To Do.
Microsoft To Do is available for iOS, Mac, Android, Windows and the Web. A Frequently Asked Questions document about the Wunderlist-to-To Do transition is here.