A while ago I made a small tool called importabular, that would help me import data into ciboulette.net It's a spreadsheet like UI with named columns. It was my first attempt at writing a spreadsheet UI and there were some issues. It was trying to do too much, and was too specific for one use case, and the lack of virtualization brought some issues.
Today I worked on a new version and I'm quite happy with the result. Given that the project scope and data model are quite different, I picked a new name. NanoSheets was free, and puts the emphasis on how light that lib is (2.5Kb minified and gzipped). The other libraries in this domain seem to all be Swiss army behemoth where you first need to turn off 90% of the features.
Anyway, here's the demo website : https://nanosheets.lecaro.me/