Microsoft bought Wunderlist creator 6Wunderkinder in 2015 and announced To Do (or To-Do, as it was known then) in April 2017. It launched a redesigned version of To Do in September, which brought the service closer in line with Wunderlist's feature set while deepening its integration with several Microsoft services, including Outlook, Microsoft Planner and Cortana.

The plan to put Wunderlist out to pasture has been in the works for a long time. Despite founder Christian Reber's offer to buy back the service, it'll wind down in less than five months.