Free and open software makers can be found throughout the tech world. From your datacenter to the desktop and everywhere in between; there’s an open solution to your computing needs. These applications personify the innovation and ingenuity of the FOSS (Free and Open Source Software) world. All of these applications (except one) are cross-platform so you can find appropriate versions on whatever you run (BSD, Mac OSX, Linux or Windows) The examples herein, however, will be catered to the largest install base (statistically): Microsoft Windows.”]
Source: https://www.csoonline.com/article/2125011/5–great–open-source-desktop-security-applications.html