We are welcoming all kinds of contributions:
- bug reports
- proposals for changes and new features
- documentation
- fixes for the language in GUI and web (Thonny's main developers don't speak English natively)
- plug-ins (a guide is in the works, see https://bitbucket.org/KauriRaba/thonny-microbit for now)
- bug fixes
- creating and maintaining Linux packages (see https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=857042)
- tests
- refactorings
- ...
See the wiki for more info.