How to build a website change monitor that screenshots and diffs on a schedule

How to Build a Website Change Monitor That Screenshots and Diffs on a Schedule Uptime monitors check status codes. They don't catch: a competitor updating their pricing page, a third-party embed breaking your layout, a CSS regression from a deploy two days ago, or a widget that loaded fine yesterday but now shows an error. Visual change monitoring captures screenshots on a schedule and diffs each one against the previous capture. If pixels change beyond a threshold, you get an alert. The architecture cron → screenshot all watched URLs → compare to stored baseline → if diff > threshold → alert → update baseline Core monitor script import fs from " fs/promises " ; import path from " path " ; import { PNG } from " pngjs " ; import pixelmatch from " pixelmatch " ; import nodemailer from " nodemailer " ; const CONFIG = { pages : [ { name : " Competitor pricing " , url : " https://competitor.com/pricing " }, { name : " Your homepage " , url : " https://yourapp.com " }, { name : " Status page