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mcp-nodejs-debugger

Debug Node.js applications at runtime, enabling the identification and resolution of issues efficiently. Integrates with tools like Cursor and Claude Code for enhanced debugging capabilities.

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mcp-nodejs-debugger logo

workbackai

No License

Quick Info

GitHub GitHub Stars 283
NPM Weekly Downloads 0
Tools 1
Last Updated 2026-02-19

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debuggerdebuggingdebugnodejs debuggerdebug nodedebugging capabilities

MCP Node.js Debugger

An MCP server that gives Cursor or Claude Code access to Node.js at runtime to help you debug: @hyperdrive-eng/mcp-nodejs-debugger.

Demo

Cursor

https://github.com/user-attachments/assets/c193a17e-b0e6-4c51-82aa-7f3f0de17e1a

Claude Code

https://github.com/user-attachments/assets/adb7321b-3a6a-459b-a5c9-df365710d4d8

Quick start

Cursor

  1. Add to Cursor (~/.cursor/mcp.json)

    image

    diff + { + "mcpServers": { + "nodejs-debugger": { + "command": "npx", + "args": ["@hyperdrive-eng/mcp-nodejs-debugger"] + } + } + }

  2. Run a Node.js server in debug mode (i.e. with the --inspect flat)

    sh node --inspect {file.js}

  3. Ask Cursor to debug your Node.js server at runtime

    image

Claude Code

  1. Add to Claude Code

    sh claude mcp add nodejs-debugger npx @hyperdrive-eng/mcp-nodejs-debugger

  2. Start Claude Code

    sh claude ╭───────────────────────────────────────────────────────╮ │ ✻ Welcome to Claude Code research preview! │ │ │ │ /help for help │ │ │ │ Found 1 MCP server (use /mcp for status) │ ╰───────────────────────────────────────────────────────╯

  3. Run a Node.js server in debug mode (i.e. with the --inspect flat)

    ```sh

    In another terminal

    node --inspect {file.js} ```

  4. Ask Claude Code to debug your Node.js server at runtime

    ```sh

    I'm getting a runtime error in Node.js

    {YOUR_RUNTIME_ERROR}

    Please help me debug this error at runtime using the nodejs-debugger mcp. ```

Usage

Claude Code

  1. Add to Claude Code

    sh claude mcp add nodejs-debugger npx mcp-nodejs-debugger

  2. Verify connection

    ```sh

    /mcp ⎿ MCP Server Status

     • nodejs-debugger: connected

    ```

  3. Remove from Claude Code

    sh claude remove nodejs-debugger

Cursor

  1. Add to Cursor (~/.cursor/mcp.json)

    diff + { + "mcpServers": { + "nodejs-debugger": { + "command": "npx", + "args": ["@hyperdrive-eng/mcp-nodejs-debugger"] + } + } + }

  2. Verify connection:

    image

  3. Remove from Cursor (~/.cursor/mcp.json):

    diff - { - "mcpServers": { - "nodejs-debugger": { - "command": "npx", - "args": ["@hyperdrive-eng/mcp-nodejs-debugger"] - } - } - }

Example

Cursor

  1. Run this simple Node.js app: github.com/mdn/express-locallibrary-tutorial:

    sh node --inspect ./bin/www

  2. Ask Cursor to set a breakpoint

    image

    image

  3. Create a book at localhost:3000/catalog/book/create

    image

  4. Watch Cursor capture runtime state

    image

Claude Code

  1. Here is a buggy Node.js server:

    ``` node --inspect index.js

    Debugger listening on ws://127.0.0.1:9229/2862f5a2-8618-4516-8429-1248b397e9b4

    THE RUNTIME ERROR

    MongooseServerSelectionError: Could not connect to any servers in your MongoDB Atlas cluster. One common reason is that you're trying to access the database from an IP that isn't whitelisted. Make sure your current IP address is on your Atlas cluster's IP whitelist: https://www.mongodb.com/docs/atlas/security-whitelist/ at _handleConnectionErrors (/Users/arthur/Documents/thirdparties/mdn/express-locallibrary-tutorial/node_modules/mongoose/lib/connection.js:1110:11) at NativeConnection.openUri (/Users/arthur/Documents/thirdparties/mdn/express-locallibrary-tutorial/node_modules/mongoose/lib/connection.js:1041:11) at async main (/Users/arthur/Documents/thirdparties/mdn/express-locallibrary-tutorial/app.js:35:3) { reason: TopologyDescription { type: 'ReplicaSetNoPrimary', servers: Map(3) { 'ac-8e6hgk7-shard-00-01.cojoign.mongodb.net:27017' => [ServerDescription], 'ac-8e6hgk7-shard-00-02.cojoign.mongodb.net:27017' => [ServerDescription], 'ac-8e6hgk7-shard-00-00.cojoign.mongodb.net:27017' => [ServerDescription] }, stale: false, compatible: true, heartbeatFrequencyMS: 10000, localThresholdMS: 15, setName: 'atlas-5syy8t-shard-0', maxElectionId: null, maxSetVersion: null, commonWireVersion: 0, logicalSessionTimeoutMinutes: null }, code: undefined } ```

  2. Claude Code debugs the Node.js server at runtime:

    ```sh

    I'm getting a runtime error connecting to mongoose. Please help me debug by checking the value of the mongodb configs at runtime using the nodejs-debugger mcp.

    ⏺ I'll help you debug the mongoose connection issue using the Node.js debugger. Let's first understand where the MongoDB connection is configured.

    ⏺ Search(pattern: "*/.js")… ⎿  Found 100 files

    ⏺ Let's set a breakpoint at the mongoose connection point and continue:

    ⏺ nodejs-debugger:set_breakpoint (MCP)(file: … "/Users/arthur/Documents/thirdparties/mdn/express-locallibrary-tutorial/app.js", line: 35)   ⎿  Breakpoint set successfully. ID: 2:34:0:file:///Users/arthur/Documents/thirdparties/mdn/express-locallibrary-tutorial/app.js

    ⏺ Let's list all our breakpoints:

    ⏺ nodejs-debugger:list_breakpoints (MCP)   ⎿  [ { "file": "/Users/arthur/Documents/thirdparties/mdn/express-locallibrary-tutorial/app.js", "line": 35, "id": "2:34:0:file:///Users/arthur/Documents/thirdparties/mdn/express-locallibrary-tutorial/app\.js" } ]

    ⏺ Let's try to execute a specific piece of code to check the connection variables:

    ⏺ nodejs-debugger:nodejs_inspect (MCP)(js_code: "// Get the mongoose module and inspect connection\nconst mongoose = … require('mongoose');\nconsole.log('Current mongoose version:', mongoose.version);\nconsole.log('Current mongoose connection state:', mongoose.connection.readyState);\n// Log connection string safely (without password)\nconst connectionString = process.env.MONGODB_URI || \n \"mongodb+srv://cooluser:coolpassword@cluster0.cojoign.mongodb.net/local_library?retryWr ites=true&w=majority&appName=Cluster0\";\nconsole.log('Connection string (masked):', connectionString.replace(/(?<=mongodb\+srv:\/\/\w+:)(.+?)(?=@)/, '*'));")

    ⎿  Console output: [log] Current mongoose version: 8.9.5 [log] Current mongoose connection state: 0 [log] Connection string (masked): mongodb+srv://cooluser:coolpassword@cluster0.cojoign.mongodb.net/local_library?retryWri tes=true&w=majority&appName=Cluster0

    ⏺ The runtime error you're seeing in your application is related to MongoDB Atlas connection issues. Based on your error message, the problem is:

    1. You're using placeholder credentials ("cooluser:coolpassword")

To fix this, you have two options:

1. Use a local MongoDB instance by changing line 29-30 in app.js to:
const dev_db_url = "mongodb://127.0.0.1:27017/local_library";
2. Or correctly set up MongoDB Atlas:
  - Log into Atlas at https://cloud.mongodb.com
  - Go to Network Access and add your current IP to whitelist
  - Create proper database credentials
  - Update the connection string with real credentials

Which option would you like to proceed with?

    ```

See Also

Claude
Claude PNG Icons
Connection 1x
Connection 1x PNG Icons
MCP
Code Mcp
Cursor
Cursor PNG Icons
Mongoose
Mongoose PNG Icons
← Back to Task And Project Management🙏  Credits & Acknowledgments
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