Under the group name “APLTeam” two Open Source libraries (MIT license) are hosted on GitHub with projects somehow connected to Dyalog APL:

The APLTree library

A library with Dyalog APL classes and namespace scripts that aim to support the Dyalog APL programmer on many every-day problems.

The APL-cation projects

A collection of applications and user commands implemented in Dyalog APL which aim to support the Dyalog APL programmer during the development cycle or are useful in other ways.

Since these are all Open Source projects under the quite relaxed MIT license, everybody is welcome to contribute.

However, until further notice it's me, Kai Jaeger, who is in charge of those projects.