Popup Window is intended to make your desktop tidier by hiding windows and offering a quicker way to access them. It works by making windows accessible from the desired screen edge. The tool becomes very easy to use once you master the basics; however, it is quite unlikely that you know what to do from the start, which is why watching its tutorial video is almost indispensable.
The application is meant to be unobtrusive, so it is quite convenient that it does not use screen space. Instead, it runs from the Menu Bar, from where you can access its preferences. In this respect, you can pick the screen edge you want to use to keep your windows collapsed. However, although it supports using hotkey combinations for different functions, it is not possible to customize them. Actually, I think the tool could be made much easier to use if it allowed dragging windows to the screen edge to make them available as tabs.
All in all, Popup Window can help you have a more organized desktop. Regrettably, I find that the app’s workflow may actually interfere with your productivity, mainly if you hate memorizing hotkey combinations as I do. The product’s latest version is available from the Mac App Store and it does not seem to support macOS latest version. Even though there is a trial version you can download from the developer’s site, it is already obsolete. Finally, I must say that I find the price of this product too high.