Hi thanks for the comment, you can check in this repo https://github.com/Rodrigolmti/flutter_clean_architecture the folder organization that a figure out that works for me. And about the examples in English and dart files i just fixed. And abou the single SignInUseCase i think it's up to you and your project, in my last project i did one single use case that handles appointmens, so inside it i can open a new appointment, close the last one, and have some validations logics.