Fiji / ImageJ
https://fiji.sc/
https://imagej.net/Category:Plugins
Fiji is easy to use and install – in one-click, Fiji installs all of its plugins, features an automatic updater, and offers comprehensive documentation. Fiji bundles together many popular and useful ImageJ plugins for image analysis into one installation, and automatically manages their dependencies and updating.
https://www.youtube.com/user/fijichannel
QuPath
https://qupath.github.io/
SharedScripts-StarDist (creating training Images for StarDist)