Have you ever opened an Excel file and felt a pang of unease? Rows upon rows of data, cryptic formulas sprawled across cells, and a tangle of manual formatting that seems one misstep away from chaos.

Microsoft Excel has been the industry standard spreadsheet software for decades, since outdoing the once venerable Lotus 1-2-3, the first killer app for PCs in the 1980s. And Excel's dominance has yet ...