Node.js Sandbox

Node.js Sandbox MCP Server

A Node.js–based Model Context Protocol server that spins up disposable Docker containers to execute arbitrary JavaScript.

What is an MCP Server?

MCP Info

Image Building Info

Available Tools (7)

Tools Details

Tool: get_dependency_types

Given an array of npm package names (and optional versions), fetch whether each package ships its own TypeScript definitions or has a corresponding @types/… package, and return the raw .d.ts text.

Useful whenwhen you're about to run a Node.js script against an unfamiliar dependency and want to inspect what APIs and types it exposes.

Tool: run_js

Install npm dependencies and run JavaScript code inside a running sandbox container. After running, you must manually stop the sandbox to free resources. The code must be valid ESModules (import/export syntax). Best for complex workflows where you want to reuse the environment across multiple executions. When reading and writing from the Node.js processes, you always need to read from and write to the "./files" directory to ensure persistence on the mounted volume.

Tool: run_js_ephemeral

Run a JavaScript snippet in a temporary disposable container with optional npm dependencies, then automatically clean up. The code must be valid ESModules (import/export syntax). Ideal for simple one-shot executions without maintaining a sandbox or managing cleanup manually. When reading and writing from the Node.js processes, you always need to read from and write to the "./files" directory to ensure persistence on the mounted volume. This includes images (e.g., PNG, JPEG) and other files (e.g., text, JSON, binaries).

Example:

import fs from "fs/promises";
await fs.writeFile("./files/hello.txt", "Hello world!");
console.log("Saved ./files/hello.txt");

• mcr.microsoft.com/playwright:v1.55.0-noble: Playwright image for browser automation. (Preconfigured for running Playwright scripts.)
• alfonsograziano/node-chartjs-canvas:latest: Chart.js image for chart generation and mermaid charts generation. ('Preconfigured for generating charts with chartjs-node-canvas and Mermaid. Minimal Mermaid example: import fs from "fs"; import { run } from "@mermaid-js/mermaid-cli"; fs.writeFileSync("./files/diagram.mmd", "graph LR; A-->B;", "utf8"); await run("./files/diagram.mmd", "./files/diagram.svg");)

Tool: sandbox_exec

Execute one or more shell commands inside a running sandbox container. Requires a sandbox initialized beforehand.

Tool: sandbox_initialize

Start a new isolated Docker container running Node.js. Used to set up a sandbox session for multiple commands and scripts.

Tool: sandbox_stop

Terminate and remove a running sandbox container. Should be called after finishing work in a sandbox initialized with sandbox_initialize.

Tool: search_npm_packages

Search for npm packages by a search term and get their name, description, and a README snippet.

Use this MCP Server

{
  "mcpServers": {
    "node-code-sandbox": {
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "mcp/node-code-sandbox"
      ]
    }
  }
}

Why is it safer to run MCP Servers with Docker?