Ask HN: Looking for a Show HN posted here a while ago

I remember a Show HN posted here, the result of someone's university thesis/dissertation. Problem is I only partially remember what it was.

It was something in this space; like jupyter notebooks or a content-editable like editor.

There was a website showcasing all its features, it looked very solid and polished.

I know there's not too much to go on here, but I hope someone here knows what I'm talking about.