This program allows you to raise your own environment on the server for communication among colleagues and it is easy to install and use. It is this application that is considered a good replacement for Slack or Skype.
PidGin is a utility that allows you and your friends/colleagues to communicate in it. It is cross-platform and easy to install, and it also has a fairly clear and pleasant interface to work with.
Editors
Ardour - An application that can be used from different operating systems. You can use it to edit, listen to and mix audio files. With a nice interface and a fairly clear principle of operation.
Transitions DJ - The capabilities of this b2b email list program are very impressive, for example, with its help you can mix or mix compositions during live performances. It also has other features that it is better for you to get to know in person.
Gimp - Is considered a free replacement for Photoshop. This application is easily installed into the system and has a fairly intuitive interface.
IncScape - Photo editor, which can also be considered a good replacement for Photoshop. It is distributed for free and has functionality like Gimp, but not everyone likes the functionality / interface of the first one, so they use this editor.
OpenShot - Free replacement of SonyVegas and other video editors. This application is cross-platform, which is why it can be used even on Windows. It has a nice interface and good functionality, which is why you can make beautiful videos.
Blender is an application in which you can edit videos, and it also has great functionality that will allow the user to work with 3D animation and so on. Initially, it is difficult to work with this application, but it has extensive documentation that will help you understand its interface and functionality.
Replacing MSOffice
LibreOffice is a great free replacement for MS Office that provides the same functionality. It is easy to install and has a clear and pleasant interface.