Hi wsih, thanks! There is a lot to unpack on those threads but of the top of my head: 1. Clear separation between UX/backend Done by design in IronCalc. It is first a spreadsheet engine.

2. Multi language support, language connectivity, enhanced data types, ...

You might very well be right, but out first step is to be as close to Excel as possible. We are ~ 1 year away from being formula compatible in a reasonable way. Once we are there we can do better in different directions. I think strict typing might be very beneficial for spreadsheets engines. Anything you can do to reduce errors and human mistakes.

I strongly believe that having a competitive spreadsheet engine fully open source might be a good first step in extending and improving Excel.

Let's see!

I am sure you are in the right track! It would also be great to know if you have some kind of business model on mind.

Noup. I'm not doing this for money. Not saying there is not a business angle, and happy to help anyone that wants to build a business using IronCalc.

Hyperfiddle and Quadratic implement some of the items on your wishlist (richer data types, modern programming languages, working with arrays, better connectivity to data tools).

They are both amazing tools!