A developer has built Site Spy, a browser extension that monitors specific webpage elements and delivers changes via RSS feeds. The tool emerged from a personal frustration when the creator missed a visa appointment because they didn't notice a government website update for two weeks. Unlike traditional page monitoring tools that track entire noisy pages, Site Spy lets users watch just one element like a price, stock status, or headline.

Available as both Chrome and Firefox extensions with a web dashboard, Site Spy offers element-level tracking through an inspector tool, visual diff views showing additions in green and removals in red, and RSS feeds for individual watches or tags. The tool also includes an MCP server for AI assistants like Claude and Cursor, plus notifications through browser push, email, and Telegram. Users can set monitoring intervals from minutes to weeks and browse a timeline of captured snapshots.

The creator is seeking feedback on whether RSS feeds are actually useful compared to direct alerts, and if element-level tracking provides meaningful advantages over full-page monitoring. With free and paid tiers starting at €4 per month, Site Spy aims to solve the problem of missing important website updates in an increasingly dynamic web.