I built a free payroll checker that runs 100% in your browser, your file never leaves your computer

The whole thing is built around one rule: payroll is salary data, so the file should never be uploaded anywhere. It runs entirely in your browser, nothing is sent to any server, and it even works offline. That was the non-negotiable, because the people who do this are (rightly) paranoid about where that data goes. What it does: drop in this pay period and the last one, and it flags what shouldn’t have changed. Someone terminated who’s still getting paid, a brand new name that shouldn’t be there yet, a number that jumped more than your threshold. You can also drop in a single file to catch the basic stuff (duplicate IDs, missing values, numbers that look off). Free, no signup, no upload. I’d love blunt feedback: is it actually useful, or is it missing something obvious? Link in the comments.