The APL-Cation project is an Open Source project; all members run under the — quite relaxed — MIT license.
For a list with all members and information regarding features and platform availability see the Members page.
Note that prior to 2018-02 some of those applications have been part of the APLTree library. They are now independent from the APLTree project which is now a pure library for Dyalog APL. This does not change anything regarding licensing etc. but makes managing them easier.
You can download or clone any project from it's own project page on GitHub. The page https://download.aplwiki.com/ is now retired.
Potentially Windows, Linux and Mac OS are supported. There are no plans to support AIX and the PI.