Shelfit is described as 'Worry less about juggling multiple windows or deciding where you want to store things. With Shelfit you can quickly open up a shelf, drag files in, and then when you're ready just drag them back out' and is a File Manager in the backup & sync category. There are more than 10 alternatives to Shelfit for a variety of platforms, including Mac, Windows, Linux, Web-based and iPhone apps. The best Shelfit alternative is Tokri, which is both free and Open Source. Other great apps like Shelfit are Droppy for macOS, Dockside, Yoink and ShakePin.