Yes, Code Runner is free to use.

How do I install Code Runner?

Code Runner is a local plugin. Install it using npm package: mcp-server-code-runner and add the generated configuration snippet to your AI app's MCP config file. Then restart your AI app.

What AI apps work with Code Runner?

Code Runner uses the Model Context Protocol (MCP) and works with any MCP-compatible AI app, including Claude, ChatGPT / Codex, Gemini, Copilot, Cursor, and more.

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Code Runner MCP Server

by formulahendry

Developer ToolsModerate7.2Local

Free

Code Runner MCP Server which can run code in various programming languages.

About

Code Runner MCP Server which can run code in various programming languages.

Security Report

7.2

Moderate7.2Low Risk

Valid MCP server (4 strong, 4 medium validity signals). 1 code issue detected. 3 known CVEs in dependencies (0 critical, 3 high severity) Package registry verified. Imported from the Official MCP Registry. Trust signals: trusted author (4/4 approved). 1 finding(s) downgraded by scanner intelligence.

9 files analyzed · 5 issues found

Security scores are indicators to help you make informed decisions, not guarantees. Always review permissions before connecting any MCP server.

Permissions Required

This plugin requests these system permissions. Most are normal for its category.

env_vars

Check that this permission is expected for this type of plugin.

file_system

Check that this permission is expected for this type of plugin.

Shell Command Execution

Runs commands on your machine. Be cautious — only use if you trust this plugin.

How to Install

Add this to your MCP configuration file:

{
  "mcpServers": {
    "io-github-formulahendry-code-runner": {
      "args": [
        "-y",
        "mcp-server-code-runner"
      ],
      "command": "npx"
    }
  }
}

Documentation

View on GitHub

From the project's GitHub 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"
        ],
      }
    }
  }
}

npx for Claude Desktop

Configuration in claude_desktop_config.json:

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

Docker

Use VS Code as example. 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": "docker",
        "args": [
          "run",
          "--rm",
          "-i",
          "formulahendry/mcp-server-code-runner"
        ]
      }
    }
  }
}

npx issue on Widnows

On Windows, MCP servers may fail to connect with npx.

You could try below two workarounds:

use bunx

Install Bun.
In configuration, change npx with bunx.

use cmd

Below is VS Code configuration in settings.json:

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

Run with Streamable HTTP Transport

npm install -g mcp-server-code-runner@latest
mcp-server-code-runner --transport http

Usage

Before using Code Runner MCP Server, please make sure interpreter or compiler of the programming language you want to run is set in PATH environment variable.

Try below prompts in the application which has configured Code Runner MCP Server: