Extensiondev MCP Server

by extensiondev Your server? Claim it

local only

Extensiondev runs on your own machine — the client starts it, so there is no endpoint to ping. 524 installs a week from npm. Last commit 2 Nov 2026.

Build, run, inspect, and publish browser extensions from any MCP client. 35 tools, 13 browsers.

Installs per day peak 802 · avg 174 · -30% w/w

a month agotoday

524

Installs / week

npm · @extension.dev/mcp

Stars

1 open issue

2 Nov 2026

Last commit

33 releases in 90 days

Apache-2.0

License

TypeScript

What the code does

We read the source, 22 h ago · rules 995398eba69f

Capabilities

What this server is able to do. For an MCP server this is often the job itself — a terminal server runs commands because that is what it is for. Listed so you know what you are plugging in, not as an accusation.

Runs an external command src/cross-spawn.d.ts:12, src/lib/profile-carryover.ts:77, src/lib/approval-open.ts:43

  function spawn(

Builds a file path from a variable src/lib/project-manifest.ts:23, src/lib/scaffold-scripts.ts:78, src/lib/capture.ts:153 и ещё 11

    path.join(root, "dist", browser, "manifest.json"),

Builds a database query by concatenation src/tools/login.ts:484

            ? `Drop or fix ${missing.join(", ")} and run extension_auth (action: login) again with the rest`

Executes code built at runtime src/lib/one-expression.ts:22

  return parses((body) => new Function(body), source);

Is this your server and something here is wrong? Tell us — corrections are free and do not require a plan.

This code can reach further than it looks

We found places where it runs commands, builds paths or queries from values it is given. None of that is a flaw by itself — it becomes one when the code changes, and code changes quietly between releases. We re-read it on every one.

Connect this server

This server runs on your own machine — install it with the package manager and the client starts it for you. Package name taken from the official registry entry.

Claude Code Claude Desktop Codex Cursor VS Code

run in your terminal

claude mcp add mcp -- npx -y @extension.dev/mcp

~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@extension.dev/mcp"
      ]
    }
  }
}

~/.codex/config.toml

[mcp_servers.mcp]
command = "npx"
args = ["-y", "@extension.dev/mcp"]

.cursor/mcp.json

{
  "mcpServers": {
    "mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@extension.dev/mcp"
      ]
    }
  }
}

.vscode/mcp.json

{
  "servers": {
    "mcp": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "@extension.dev/mcp"
      ]
    }
  }
}

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Extensiondev — questions

Answers built from our own checks of this server.

Why is there no uptime for Extensiondev?

Extensiondev runs on your own machine over stdio — there is no network address to reach, so uptime cannot be measured for it by anyone. What can be measured is adoption: the npm package @extension.dev/mcp was installed 524 times last week.

How do I connect Extensiondev?

Copy the ready config from this page. We generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each in the form that client actually reads. It runs locally, so the command pulls @extension.dev/mcp straight from npm; nothing to host, nothing to sign up for.

How many people use Extensiondev?

The npm package @extension.dev/mcp was installed 524 times in the last week. Week over week that is -30%. We show installs rather than GitHub stars on purpose: a star is a bookmark, an install is someone actually running it.

Is Extensiondev open source?

Yes — it is published under the Apache-2.0 licence, written in TypeScript, 0 stars on GitHub and 1 open issue. The source link is on this page, so you can read exactly what it does with your data before you connect it.