AI Website Annotation Extension Simplifies Visual Editing Prompts for Developers
Quick Reads
- MarkUp is a free Chrome extension that lets you annotate live webpages and send visual briefs to AI agents.
- The tool captures CSS selectors automatically, so your AI agent targets the exact webpage element.
- There is no backend server, all annotation data stays in your browser’s local storage.
- MarkUp works with Claude, ChatGPT, and Microsoft Copilot, and supports Chrome, Edge, Brave, and Arc.
- The first 500 beta testers who share feedback will receive lifetime free access when the Pro tier launches.
If you have ever struggled to explain a website change to an AI agent in words, MarkUp may just solve that forever. The free Chrome extension, launched on Product Hunt this week, gives users a drawing canvas directly on any live webpage. You annotate what needs changing, label each element, and export a clean structured brief to your AI tool of choice.
The maker, Michael Castelo, built MarkUp out of personal frustration. He was spending too much time writing long prompts to describe visual web changes. Instead, MarkUp turns the live webpage itself into the prompt. Users simply draw on the page, number each change, and send a ready-to-use brief to Claude, ChatGPT, or Microsoft Copilot.
Notably, the tool captures CSS selectors with every annotation. Therefore, your AI agent does not guess which element you mean, it knows the exact path. That level of precision is a significant step forward for AI-assisted web development workflows.
MarkUp is currently in early access and, furthermore, requires no account to use. Additionally, the extension has no backend server and makes zero network requests. All annotation data stays in your browser’s local storage. Consequently, privacy-conscious users and enterprise teams can use it without concern.
The extension currently works on Chrome, Edge, Brave, and Arc. Meanwhile, a Safari Web Extension is already in the works. Castelo also mentioned that a Pro tier is coming after early access ends. However, the first 500 beta testers who share feedback earn lifetime free access at launch.
For developers working with AI coding agents, MarkUp exports directly to a local folder the agent watches. The markdown changelog includes CSS selectors so tools like Claude Code know exactly which element to target. That makes it a compelling tool for anyone in the vibe-coding or AI-first development space.
The launch has already drawn attention within the Product Hunt community, where Castelo is actively fielding questions and feature requests. Given the growing demand for structured AI prompts in web workflows, MarkUp is clearly tapping into a real and underserved pain point.
