[izuchukwu]

It was most likely Subset: https://news.ycombinator.com/item?id=36894939

It appears they are re-engineering their product, as they've taken down their sign up link and their landing page now advertises an upcoming, more traditional spreadsheet product: https://subset.so/

Their docs are still up, however, and has screenshots from their old infinite canvas spreadsheet product: https://docs.subset.so/