Here is a short list of popular free apps for MacOS.
Termius – SSH client, there is also a version for iOS.
iTerm – terminal.
Telnet is a simple telnet client.
ForkLift – SFTP and FTP client.
VirtualBox – virtualization software, great for tests, you can create separate internal networks between virtual machines.
PaintS is a simple image editor, you can quickly crop a picture, etc.
GIMP – image editor (downloaded from the site).
iMovie is an intuitive and convenient video editor.
Screen Recorder Lite – record video from the screen (in the free version, you can record up to 120 seconds).
LibreOffice is a popular set of office applications (downloaded from the site).
VLC media player – player for video.
Transmission – torrent.
AppCleaner – for the complete removal of applications (downloaded from the site).
Thunderbird is a popular email client, but you can use the built-in one.
Phone is a simple SIP client, I connect it to the asterisk server.
Telegram, Skype, Viber.
Tincta, Atom (download from site).