I had ChatGPT build me a free PDF editor because I didn't trust it to change my files - it worked!

The smartest way to use AI may not be letting it touch your files, but asking it to write software that handles them safely - ...
GitHub

Libxlsxwriter: A C library for creating Excel XLSX files.

Libxlsxwriter is a C library that can be used to write text, numbers, formulas and hyperlinks to multiple worksheets in an Excel 2007+ XLSX file.