mcp-server-code-runner

MCP.Pizza Chef: formulahendry

Rather than describing what a piece of code would do, your assistant can run it and show you the output, across roughly forty languages including Python, JavaScript, Ruby, Go, PowerShell, and shell scripts. The catch is that each language only works if it is already installed on your computer, and the code runs with your own permissions unless you choose the Docker version. No key or account is needed, and setup is a short block pasted into VS Code or Claude Desktop.

Coding

Data

Use This MCP server To

Check what a snippet actually prints before trusting it Do a quick calculation the model might otherwise fumble Test a small Python or JavaScript script instantly Ask a real question about my computer and get a real answer Compare how the same idea behaves in two languages

README

Code Runner MCP Server

MCP Server for running code snippet and show the result.

It supports running multiple programming languages: JavaScript, PHP, Python, Perl, Perl 6, Ruby, Go, Lua, Groovy, PowerShell, BAT/CMD, BASH/SH, F# Script, C# Script, VBScript, TypeScript, CoffeeScript, Scala, Swift, Julia, Crystal, OCaml Script, R, AppleScript, Elixir, Clojure, Racket, Scheme, AutoHotkey, AutoIt, Kotlin Script, Dart, Haskell, Ni, Lisp, Kit, V, SCSS, Sass. Full list could be seen here in constants.ts.

Setup

npx for VS Code

Install the Code Runner MCP server in VS Code using below buttons:

Alternatively, you can add configuration in settings.json:

{
  "mcp": {
    "inputs": [],
    "servers": {
      "mcp-server-code-runner": {
        "command": "npx",
        "args": [
          "-y",
          "mcp-server-code-runner@latest"
        ],
      }
    }
  }
}

mcp-server-code-runner FAQ

Do I need a key or an account?

No. It runs entirely on your own machine and costs nothing beyond what your assistant already costs.

Can I use this to run Python if Python is not installed?

No. It calls whatever is already on your computer, so a language only works once you have installed it yourself.

Is it safe to let an assistant run code on my machine?

Treat it with care. Code runs with your own permissions and can touch your files. The Docker version keeps it walled off from the rest of your computer, which is the safer choice.

Can it edit or save my project files?

Not really. It takes a snippet, runs it, and hands back the output. Anything a script writes to disk is a side effect, not a managed feature.

Which apps does it work in?

VS Code has one-click install buttons, Claude Desktop takes a pasted block, and anything with a standard MCP configuration will also work.

How hard is the setup?

Easy. Click the install button in VS Code, or paste three lines into your settings file. Windows users may need a small tweak noted in the instructions.

Is it still maintained?

Yes, though updates are occasional. The most recent code change was February 2026.