I lost a deal last month. Prospect told me my competitor had dropped Started looking for a tool to automate this. So I built one. Next.js 16 (App Router) Playwright for scraping Supabase for storage Resend for emails vercel for hosting and cron worker The hardest part: signal vs noise Generic page monitoring is easy. Meaningful A pricing page changes constantly, rotating I built a classification engine that categorizes PRICE_CHANGE — dollar amounts moving PLAN_CHANGE — plans appearing or disappearing FEATURE_CHANGE — features shifting between tiers COSMETIC — everything else (ignored) The key insight: normalize the text before diffing. Strip dates, times, navigation text, cookie notices, social handles. Then run a line-by-line diff on what's left. Only PRICE_CHANGE, PLAN_CHANGE, and FEATURE_CHANGE trigger an email. Why Playwright over Puppeteer Pricing pages are almost always JS-heavy SPAs. Puppeteer struggles with modern React apps,content loads after the initial HTML response. Playwright with waitUntil: 'networkidle' plus a 2 second additional wait handles even the most aggressive lazy-loading. Worth the slightly heavier dependency. The cron worker Runs at 9am daily. Processes monitors sequentially with a 3 second delay between each — not parallel. Parallel scraping gets you rate-limited and blocked fast. On first run: saves a baseline snapshot. On subsequent runs: diffs against the previous snapshot, classifies the change, sends alert if significant What I'd do differently The diff algorithm is the weakest part right now. Line-by-line text diff catches most changes but misses subtle restructuring, when a competitor moves a feature to a different plan section without changing the text, the diff doesn't catch it cleanly. Next step is extracting structured data (plan name → price → features[]) and diffing the structure instead of raw text. It's live and free https://priceblind.vercel.app/ No account, no credit card. Paste a URL, get emailed when pricing changes. Happy to answer questions about any part of the implementation, the scraping, the diff engine, or the email delivery. What would you build differently?