The app needs to be free as in beer; bonus if it’s also free as in freedom.
The basic functionality of having multiple desktops is built into the Windows API since a long time. It's mostly unknown, but documented.
SysInternals Desktops is a tool to manage such Desktops.
- it's provided by Microsoft for free (not open source)
- it works (only) on Windows
It'll show up in the Tray and create a new desktop when needed:
Windows 10 now has the new "Task View" feature built in. You can switch between desktops/spaces by clicking the new icon in the Taskbar or use the "Win-Tab" feature.
With a smart trackpad you can also switch between desktops by using a three finger swipe left/right. I prefer this with Laptops especially. You may have to turn on the feature in Windows Settings.
VirtuaWin is no cost (gratis) and open source under GPL (freedom).
Its features include:
- an N x M array of desktops, you choose the size
- assign names and keyboard shortcuts to each workspace
- assign a given window to one or all desktops
- move windows between desktops with keyboard or menu item
- define rules to open a given window or application in a given desktop
If it is for personal use, you can use Dexpot for free. I use this at home and it is excellent. A commercial single-use licence is approx 25€.
It is easy to move between desktops, have apps follow you (or not). In fact, it has a lot more power than I currently use.