So I use spreadsheet programs every day, and I don't like them.

Excel loadings became tremendously worse over time - especially when you have already opened spreadsheets, and want to open another one, you need to wait seconds until the new spreadsheet will open, and by the way Excel will move all your spreadsheets up in the windows stack because it doesn't care if you have worked in other programs right now, for Excel it will be better to rearrange your windows without asking you.

LibreOffice's Calc is not that better either. While Calc have reasonable loading speed compared to Excel, it doesn't rearrange your windows, and it's cross-platform, it still doesn't give you enough performance and UI clearance, it's still feels bloated with unnecessary features and UI elements, and you need to search all that menus to find the feature that you actually need.

And also the spreadsheet file format is somewhat compressed archive containing XML files and media files, and maybe I will try to make simpler custom format for this program, while still providing compatibility with Excel and Calc files.

The project is planned to be cross-platform, written in C with use of some libraries (at least for the quick start), and nob.h to build everything instead of make/cmake/meson or whatever.

That goal is probably too ambigous, so I will start small in the Handmade Essentials Jam 2026, and will see from there.