Free analogues of paid programs

Osalt

The project provides links to free open-source alternatives for the most used software.
By selecting the required program from the list below on the page, links will be made to the alternatives appropriate to the category for this program.

AlternativeTo

A wonderful site made by the Swedes.
It's all simple. We go in, see the list of programs with icons, click any, well, say the favorite Photoshop and get a list of alternative programs.

Say, Photoshop is not satisfied, I would like something easier, but quite effective.
By the way, you need to pay attention to the tags, because there are a lot of programs: for Windows, Linix, Mac, iOS, Android ...
By the way, Goes to another OS, say from Windows to Linux, and he needs to find Linux programs instead of the usual ones on Windows.

So, you guessed it, you can find similar applications for mobile applications. For example, I was not satisfied with Evernote and I chose Simplenote, which is much simpler, just what I need.

ReactOS

The initiative to develop a quality open source operating system that is compatible with applications and drivers for Windows.