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MCP-B/WebMCP

A feature which let's an AI develop and inject MCP servers into webpages as userscripts.

Code Demo Cerebral Valley

Core trick

Lets an AI write MCP servers as userscripts that a browser extension injects into web pages so agents can call site tools.

Tags

dev toolsagents

Description

A feature which let's an AI develop and inject MCP servers into webpages as userscripts. This MCP server can then be used by GPT-5 via the mcp-b chrome extension. I built the userscript repo which the cursor gpt-5 agent can use to test it's userscript script webmcp server. Then i built out the bridge to let the agent upload the script to the extension so the extension agent can use the tools for that website
MiguelsPizza/WebMCP★ 1.1k82 forksTypeScriptNOASSERTIONCreated Jun 13, 2025 · last push Oct 7, 2025

README excerpt

> [!IMPORTANT]
> 🚨 The WebMCP API has been accepted as a W3C deliverable and is transitioning to official web standard development. The community and all related work has moved to the [WebMCP explainer repository](https://github.com/webmachinelearning/webmcp). Please join us there! 🚨

> [!IMPORTANT]
> 📝 Repository Status: The MCP-B extension is no longer open source. This repository represents an older version of the codebase and is maintained for historical reference only. All open source content (transports, etc.) have been ported to the [WebMCP Github Org](https://github.com/WebMCP-org).



# WebMCP:

[![Chrome Web Store](https://img.shields.io/chrome-web-store/v/daohopfhkdelnpemnhlekblhnikhdhfa?style=flat-square&label=Chrome%20Extension)](https://chromewebstore.google.com/detail/mcp-b/daohopfhkdelnpemnhlekblhnikhdhfa)
[![npm version](https://img.shields.io/npm/v/@mcp-b/transports?style=flat-square)](https://www.npmjs.com/package/@mcp-b/transports)
[![License: AGPL v3](https://img.shields.io/badge/License-AGPL%20v3-blue.svg?style=flat-square)](https://www.gnu.org/licenses/agpl-3.0)
[![Build Status](https://img.shields.io/github/actions/workflow/status/MiguelsPizza/WebMCP/ci.yml?style=flat-square)](https://github.com/MiguelsPizza/WebMCP/actions)
[![GitHub stars](https://img.shields.io/github/stars/MiguelsPizza/WebMCP?style=flat-square)](https://github.com/MiguelsPizza/WebMCP/stargazers)

[🚀 Quick Start](#quick-start) • [✨ Live Demo](#live-demo) • [📚 Documentation](https://m

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