I highly recommend that anyone interested in improvements to spreadsheets check out Teapot—it has a really cool 3D cell indexing system, a type system, and lots of other features that make it fundamentally much more advanced than Excel in many ways.

A three dimensional spreadsheet sounds interesting, but the teapot site doesn’t appear to have a link to documentation on how to it works.

The download includes fairly decent documentation (although I agree it would be nice to be able to view it on the site).

I'd also like to point out the spreadsheet functionality of org-mode as a terminal based spreadsheet.

I actually started using org-mode for this feature. I had been using sc-im, but found it limiting, especially the because you cannot pass a range of cells to a custom function. In org-mode this is no problem at all, plus there are many more built in functions.

The original Lotus 1-2-3 was 'terminal' based too ....

Sure, and Visicalc before that, probably others.

I believe that VisiCalc was the first to ship a functional spreadsheet. I remember watching RichHarris’s “Rich Harris - Rethinking reactivity” video introducing Svelte 3, and he discussed an earlier academic spreadsheet concept.

https://m.youtube.com/watch?v=AdNJ3fydeao

I used the following “terminal” spreadsheets

VisiCalc on a Radio Shack Model III

Microsoft MultiPlan on MS-DOS

Lotus 1-2-3 on MS-DOS

An interesting product! It was shipped by a company (if I remember right) called "Personal Software" or some such. They marketed software they collected from individual developers.

VisiCalc was their one runaway success. So much so, they changed their name to VisiCorp.

Far less likely to support modem formats and features, though.

Visidata is a cool for exploring tabular data sets, but not a spreadsheet.