Browser extension for annotating UI elements for AI agents
Browser extension for annotating UI elements for AI agents. The onui mcp server wraps that behind the Model Context Protocol, so an assistant can use it through 1 defined tool rather than through you.
Lightweight browser extension (Chrome + Edge + Firefox) + local MCP bridge for annotation-first UI pair programming.
Everything the assistant can do here goes through one of these:
Demo — Click the preview above to play the full demo video.Installation goes through your MCP client rather than a global install: point it at pnpm on npm and it is fetched when the client starts. The copy-paste blocks for Claude Desktop, Claude Code and Cursor are further down this page.
Plenty of browser automation servers cover similar ground. The differences that matter in practice are scope of access and how much setup stands between you and a working tool call. Onui's toolset — Demo — is a fair guide to whether it matches your workflow. It is maintained by onllm-dev; worth a glance at recent repository activity before you build anything load-bearing on it.
SyncDev reviews every entry in this directory against the project's own documentation before publishing, and revisits them as servers change.
| Tool | What it does |
|---|---|
| Demo | <sub>Click the preview above to play the full demo video.</sub> |
{
"mcpServers": {
"onui": {
"command": "npx",
"args": ["-y", "pnpm"]
}
}
}Add to claude_desktop_config.json, then restart Claude Desktop.
Microsoft's official browser automation server — drive a real browser through the accessibility tree, no screenshots needed.
Industrial-strength web extraction — render, scrape, crawl and search entire sites into clean markdown.
The original Chromium automation reference server — simple, screenshot-driven browser control.
Give your coding agent the full DevTools toolbox: traces, network, console, heap snapshots and Lighthouse.
Puppeteer-powered browser control that drives pages from the accessibility tree instead of pixels.
Cloud browsers for AI agents — automation sessions that run in Browserbase's fleet, not on your machine.