Line feeds take a bit of time to go replace to make the code look pretty https://jinja.palletsprojects.com/en/2.11.x/templates/#whitespace-control Seems like adding %- to most % places like https://gitlab.com/meltano/singer-sdk/-/blob/main/cookiecutter/tap-template/%7B%7Bcookiecutter.library_name%7D%7D/%7B%7Bcookiecutter.library_name%7D%7D/streams.py#L5 would do the trick