Microsoft has put the Windows File Manager, which was in Windows since Windows 3.0 on the Microsoft Store, so it can used as an app in Windows 10. The File Manager is released as a so-called Universal Windows Platform app.
Previously, Microsoft already published the source code on the Windows File Manager on open-source hosting platform Github. This allowed users to fix bugs and to create their own version of the Windows File Manager.
Now, besides publishing the source code, Microsoft has also published the Windows File Manager in the Microsoft Store.
Windows File Manager is available for Windows 10 build 16299 or later, Windows 10 Mobile, Surface Hub and the HoloLens.