Page Diff watches any webpage and shows you exactly what shifted — visually, with a draggable before/after slider. No account. No server. Everything stays on your device.
Visual diff tool
Most webpage monitors tell you "this page changed." Page Diff shows you exactly where — with a pixel-level visual comparison you can drag across like a slider. Changed regions are highlighted with bounding boxes so you never have to hunt for what moved.
Whether it's a price drop, a new job listing, a sold-out item coming back in stock, or a competitor quietly updating their messaging — Page Diff makes the change impossible to miss.
It's a free Chrome extension that works as a page change notifier for anything on the public web — without sending your data anywhere.
Screenshots, URLs, and change history are stored in Chrome's local extension storage — on your device, under your control, forever.
Navigate to any public webpage, click Watch, and Page Diff will check it every time you visit — or on your chosen schedule.
How it works
Open any site you want to monitor — a product page, a job board, a competitor's pricing page, a news site, a government filing. If it's public and has a URL, you can watch it.
Page Diff takes a silent visual snapshot and starts watching. Choose how often to check: on visit, every 5 minutes, hourly, daily, or any custom interval in minutes or hours.
A badge appears on the extension icon the moment something shifts. Open the popup, drag the slider to explore the visual diff, dismiss to reset the baseline, and watch for the next change.
Use cases
Page Diff works as a free webpage monitor for all kinds of pages. It's a private alternative to tools like Visualping and Distill Web Monitor — no subscription, no account, and nothing sent to any server. Here are the most common reasons people use it.
Watch a product page and catch price changes the moment they happen — no browser tab open, no daily checking required.
Monitor a company's careers page for new roles without checking every day. Page Diff notifies you the moment a new position appears.
Catch the moment a sold-out event, restaurant reservation, or limited release opens back up.
Know when a competitor updates their pricing, homepage messaging, or product features — without manually checking.
See new articles appear on a publication or blog you follow closely, without subscribing to email alerts or RSS feeds.
Track government or institutional pages for policy updates, filings, or rule changes that happen without announcement.
Privacy
Screenshots are stored locally using Chrome's built-in storage. No data is sent to any server. No account is required. No third party ever sees what pages you are watching or what changed on them.
Compare that to cloud-based tools that store your screenshots remotely, require a subscription, and send you email digests of what changed on your own browser.
Page Diff does all of this locally, for free, with no sign-up. As a free website change detector, it's designed to give you full clarity without giving anything away.
Viewing modes
Drag a handle left and right to reveal the before and after states on the same frame. See the exact moment content appeared or disappeared — ideal for spotting subtle layout shifts, image swaps, or text edits that are easy to miss side by side.
View both screenshots simultaneously with colored bounding boxes marking every changed region. Ideal for comparing dense pages like news feeds, job boards, or pricing tables where multiple things changed at once.
FAQ
Yes, completely free. No subscription, no freemium limits, no account required. Install from the Chrome Web Store and start watching pages immediately with no limits on how many checks you run.
No. Everything is stored locally on your device using Chrome's chrome.storage.local API. Screenshots never leave your browser. Uninstalling the extension removes all stored data immediately.
Any publicly accessible webpage over HTTP or HTTPS. It cannot watch pages behind a login, private dashboards, or local network addresses. Static and semi-static pages — product listings, job boards, news sites, government pages — work best.
It compares screenshots pixel by pixel. Changed pixels are grouped into regions using a connected-component clustering algorithm on a 20×20 block grid, so you see bounding boxes around exactly what moved rather than a raw pixel diff. This is a true visual diff — it catches layout shifts, image swaps, and CSS changes that HTML diffs miss.
Up to 15 pages simultaneously.
You choose: on every visit, every 5 minutes, every 15 minutes, every 30 minutes, hourly, every 6 hours, daily, or any custom interval in minutes or hours.
Scheduled checks are marked as due in the background. The moment you open the watched page, the check runs automatically. Page Diff never opens tabs on your behalf.
Yes. Click the page name on any watch card to rename it inline.
Yes. Each watch keeps a lightweight history log. After dismissing a change, a collapsible history section on the card shows when previous changes were detected and how many regions were affected.
Page Diff is a free, private alternative. It does not require an account, does not store data remotely, and does not send email digests. The tradeoff is that it runs locally in your browser rather than in the cloud, so it only checks when your browser is open.
A visual diff is a comparison between two screenshots of the same page taken at different times. Rather than comparing HTML source code, a visual diff compares what the page actually looks like — so it catches changes that code diffs would miss, like image swaps, layout shifts, color changes, and anything driven by CSS or canvas rendering.
Available now
No account. No setup. Install the free Chrome extension, navigate to any webpage, and click Watch. That's it.
Install Page Diff Free