I built a web-based document comparison tool where all file parsing and diffing happens entirely in the browser. The idea came from watching non-technical coworkers struggle to compare document versions — manually reading two files side by side or fighting with Word's Track Changes. Technical details:

PDF parsing via pdf.js, DOCX via mammoth.js — all client-side Diff engine: Google's diff-match-patch Line, word, and character-level comparison Next.js 15 + TypeScript, deployed on Vercel

No files ever leave the browser. No signup required. Site: https://diffnote.net Product Hunt: https://www.producthunt.com/products/diffnote?launch=diffnot...