Developer's portal - darktable-org/darktable GitHub Wiki
1st steps in darktable development
Before diving in darktable code, start by reading Developer's guide which should be basis for understanding color, best coding practices etc.
Testing your work
All work needs to be tested, to that end, please read Chapter on testing tools in wiki. Also remember to check if your work doesn't break stuff and actually works (at least for you)
Testing work of others
In order to help with maintenance and overall quality of code, review and test code of others - check and test Pull Requests
Roadmap
Current overall needs and goals can be checked in the Roadmap
Current work
There are still things you can help with, which don't necessarily end up in the roadmap. Check active issues
Start hacking
If you think you're ready, then start Hacking on darktable
Listing all maker & modes in WB presets
$ cat data/wb_presets.json | jq '. | .wb_presets[].maker'
$ cat data/wb_presets.json | jq '. | .wb_presets[].models[].model'