Update Beacon

Monitors selected web pages at regular intervals and notifies you with a diff preview when changes are detected.

▼ What is Update Beacon? Update Beacon is a background page-monitoring extension. It watches any web page you choose, detects changes in its content, and sends you a desktop notification and toolbar badge the moment something is different. ──────────────────────────── ▼ Use cases ──────────────────────────── · Catch price drops and restocks in online stores before they sell out · Get notified when new job listings appear on recruitment sites · Track exchange rates, fund prices, or any data-rich page · Monitor news sites, government announcements, or competitor updates · Watch community boards or product pages for important keywords ──────────────────────────── ▼ Features ──────────────────────────── [Automatic Scheduled Checks] Choose from 8 check intervals: 5 min, 10 min, 30 min, 1 h, 3 h, 6 h, 12 h, or 24 h. Monitoring continues silently in the background even while you are using other tabs or have the browser minimized. [Desktop Notifications & Badge] An OS-level desktop notification fires the moment a change is found. The toolbar badge shows the count of unreviewed updates at a glance. [Before / After Comparison View] When a change is detected, open a full rendering of the old and new page to compare them directly: · Added text → highlighted in yellow · Deleted text → highlighted in red Color-coded highlights make it instant to spot exactly what changed. [Split / Single Window Mode] Toggle between modes any time via the button in the comparison header: · Split mode — old and new pages displayed side by side · Single mode — new page shown full-width for a closer look In both modes the page is rendered internally at 1280 px width and auto-scaled to fit your screen, ensuring accurate layout at any window size. [Synchronized Scrolling] In split mode, both the old and new pages scroll together. Scrolling one pane automatically moves the other to the same relative position, making long-page comparisons effortless. [Full-Page Screenshot Export] Click the camera button in the comparison header to save the entire comparison as a single PNG file named with the current timestamp: · Split mode — both panes composited side by side with "BEFORE" / "AFTER" labels and timestamps · Single mode — the new page captured in full The extension scrolls through the page tile by tile and stitches them seamlessly, so even very long pages are captured completely. [Exclude Selectors] Enter CSS selectors (e.g. `.ad, #timer`) to hide ads, countdowns, "X minutes ago" labels, and other dynamic noise from detection. Fine-tune monitoring so only meaningful changes trigger an alert. Changing the exclude selectors automatically resets the baseline snapshot. [Change Threshold] Ignore micro-edits below a word-count threshold. Only report changes when the number of differing words exceeds your chosen value. [Keyword Filter] Notify only when a specific keyword appears on the page, or only when it disappears. Perfect for tracking "In Stock", "Apply Now", or any phrase that matters to you. [Batch Open & Confirm] When multiple pages update at once, open all comparison tabs in one click from the popup header button. [Manual Check] Hit the refresh button on any card to run an immediate check without waiting for the next scheduled interval. [Acknowledge Update (Baseline Reset)] Click "Use this as new baseline" in the comparison view to accept the current snapshot as the new reference point. Future notifications will only fire when the next change occurs after this snapshot. [Drag-to-Reorder] Drag the handle on the left of each card to arrange your watch list in any order you like. [Export / Import] Save your entire watch list as a JSON file and restore it on any device. Import supports "replace all" or "add new only (skip duplicates)" modes. [Data Auto-Repair] On startup, the extension scans stored data for corruption or missing fields and repairs them automatically. Up to 5 backup snapshots are kept before any repair, so your data is always recoverable. ──────────────────────────── ▼ Privacy ──────────────────────────── Update Beacon never transmits any data to external servers. All information is stored exclusively in your browser's local storage.