Microsoft has acquired 6Wunderkinder, the company behind Wunderlist.

Microsoft published a blog post to confirm the deal, following a report from The Wall Street Journal: "What’s better than completing that last important task on your to-do list? Doing so with a beautiful and useful productivity app. Today, I am thrilled to announce that Microsoft has acquired 6Wunderkinder."

Wunderlist will continue to exist in app stores and work for the time being. The app will remain free, and there will be no price changes for Wunderlist Pro or Wunderlist Buesiness. Microsoft will likely - or rather, eventually - integrate the app's technology into its own productivity apps at some point in the future.

Wunderlist will "fit squarely" into Microsoft's product portfolio and ambition to reinvent productivity for a mobile-first, cloud-first world, Microsoft said in its post. It also referred to its exisiting productivity tools, including Office, OneNote, Skype for Business, and the recent Sunrise and Acompli acquisitions.

Ever since Satya Nadella took over the reigns at Microsoft, the Redmond-based company has been working hard to focus more on mobile apps and devices. It therefore makes perfect sense for Microsoft to buy popular apps, especially the productivity-based ones, as it is an area the company is well-known at getting right.

"Over the next few months as Wunderlist becomes a part of the Microsoft family, we’ll introduce a host of new features, continue growing the ecosystem of partner integrations and progress in delivering Wunderlist to billions of people. We are excited," Christian Reber, Wunderlist's Founder and CEO, confirmed.

Wunderlist also announced it has about 13 million customers at the moment. Its acquisition is rumored to have cost between $100 million and $200 million, but neither company has disclosed the financial details.