I built a tool that watches webpages and exposes changes as RSS
I built Site Spy after missing a visa appointment slot because a government page changed and I didn’t notice for two weeks. It watches webpages for changes and shows the result like a diff. The part I think HN might find interesting is that it can monitor a specific element on a page, not just the whole page, and it can expose changes as RSS feeds. So instead of tracking an entire noisy page, you can watch just a price, a stock status, a headline, or a specific content block. When it changes, you can inspect the diff, browse the snapshot history, or follow the updates in an RSS reader. It’s…
In plain words
Site Spy is a browser extension that monitors webpages for changes and displays them as diffs. It lets users track specific page elements rather than entire pages, making it useful for watching prices, stock status, or appointment availability without noise. Changes can be inspected as diffs, reviewed in a timeline history, or followed via RSS feeds. The tool includes a web dashboard and integrates with AI agents through an MCP server, with notifications via browser push, email, or text.
written from the facts on this page · September 2026
From the sources
In the maker’s words, at launch
I built Site Spy after missing a visa appointment slot because a government page changed and I didn’t notice for two weeks. It watches webpages for changes and shows the result like a diff. The part I think HN might find interesting is that it can monitor a specific element on a page, not just the whole page, and it can expose changes as RSS feeds. So instead of tracking an entire noisy page, you can watch just a price, a stock status, a headline, or a specific content block. When it changes, you can inspect the diff, browse the snapshot history, or follow the updates in an RSS reader. It’s a Chrome/Firefox extension plus a web dashboard. Main features: - Element picker for tracking a specific part of a page - Diff view plus full snapshot timeline - RSS feeds per watch, per tag, or across all watches - MCP server for Claude, Cursor, and other AI agents - Browser push, Email, and Telegram notifications Chrome: https://chromewebstore.google.com/detail/site-spy/jeapcpanag... Firefox: https://addons.mozilla.org/en-GB/firefox/addon/site-spy/ Docs: https://docs.sitespy.app I’d especially love feedback on two things: - Is RSS actually a useful interface for this, or do most people just want direct alerts? - Does element-level tracking feel meaningfully better than full-page monitoring?
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