I Built a Monitoring Tool Because Uptime Checks Kept Lying to Me

If you deploy sites to Netlify, Vercel, Cloudflare Pages or pretty much any modern platform — you've probably set up some kind of uptime monitoring. Ping every minute, get an alert if the server doesn't respond. Pretty standard stuff. I had the same setup across all my sites. And for a long time, I thought I was covered. I wasn't. The Problem A few months back I pushed an update to one of my Nuxt apps on Netlify. Build passed, deploy preview looked fine, dashboard showed green. I moved on. Turns out the site was broken for hours. Not down — the server was responding just fine. 200 OK on every request. But the JavaScript bundle the page needed wasn't loading, so the entire app was a blank page. Here's what happened: the new deploy generated fresh hashed bundles. main.c8d13.js replaced main.a4f2c.js . But some CDN edge nodes were still serving the old HTML, which referenced the old filename. Browser tries to fetch main.a4f2c.js , gets a 404 , and nothing renders. My uptime monitor? Green