I hadn’t come across papermill before - looks quite full featured. Seems to be oriented a bit towards “scripting Notebooks” with the ability to generate output notebook files with populated output cells. I think it must have to emulate some of the logic of the Notebook ui to do that.

NotebookScripter is much more minimal and doesn’t support generating/updating .ipynb files. It has just one api allowing one to treat a notebook file as a function that can be called from another python program.

I’m not entirely sure whether papermill can run the target notebook in the calling process — it looks like it spins up a Jupyter kernel and communicates with it via message passing. NotebookScripter creates an ipython interpreter context in process and execs the notebook code in process.