[citruspi]

Both the editor[0] and the server[1] are open source.

[0]: https://github.com/webshell/materia-designer

[1]: https://github.com/webshell/materia-server

Edit:

My bad, only the server is open source.

[thyb]

Materia server is fully open source. We are in the process of commenting it better for people to contribute and customize it.

Materia Designer is not fully open source, we use this repository as issue tracker and to keep a trace of everything.

We’re still considering open-sourcing it too to engage the community for building addons.

[citruspi]

Ah, my bad. I just saw the link, I probably should've taken 30 seconds to check out the repository contents.