Nodemon Config: Ultimate Guide to nodemon.json & CLI

Are you tired of messy CLI flags every time you run Nodemon? Want a clean, manageable, and powerful setup that saves you time and keeps your development workflow smooth? You’re in the right place.
In this article, I’ll walk you through mastering Nodemon configuration using nodemon.json, the nodemonConfig section in package.json, and command-line flags. You’ll learn how to watch specific files, ignore unnecessary folders, run custom commands, set environment variables, and debug your config—all in a way that’s easy to understand and practical to implement.

If you haven’t installed Nodemon yet, don’t worry! I’ve written a step-by-step guide on how to install Nodemon in Node.js — check it out if you need to get set up. Ready? Let’s dive into Nodemon config like a pro.

Nodemon Config with nodemon.json

By default, Nodemon looks for a nodemon.json file in the root folder of your project. This JSON file holds your configuration settings and keeps things neat and centralized.
If you want different setups—for example, one for development and one for production—you can use the --config flag to point Nodemon to another config file.

npx nodemon --config nodemon.dev.json # For Development
npx nodemon --config nodemon.prod.json # For Production

This allows switching between development and production environments.

watch: What Should Nodemon Monitor?

The watch key tells Nodemon which folders or files to monitor for changes. Without it, Nodemon watches everything by default, which can cause unnecessary restarts.

{
  "watch": ["src"]
}

ignore: What to Skip

You might want to ignore folders like logs that change often but don’t require a restart.

{
  "watch": ["src"],
  "ignore": ["src/logs"]
}

Keep in mind: the ignore key prevents restarts when files change in those folders but Nodemon still monitors them. To fully exclude a folder, ensure it’s not in the watch array at all.

Watch & Ignore Patterns

You can use these patterns with watch and ignore rules:

• "src/" watches the whole src folder.
• "src/*" watches all files directly in the src folder.
• "src/*.js" watches only .js files in src folder.
• "src/**/*.js" recursively watches all .js files in src folder and its subfolders.

Be careful— ignore patterns must be absolute paths. Relative ones can behave unexpectedly.

Both watch and ignore are arrays. You can add multiple folders to watch or ignore. For example, you can add the config folder to the watch list and ignore the tmp folder inside src:

{
  "watch": ["src", "config"],
  "ignore": ["src/logs", "src/temp"]
}

ext: Extensions to Watch

The ext key instructs Nodemon to only restart the process when files with specific extensions change. It is useful for projects with mixed file types.

{
  "watch": ["src"],
  "ignore": ["src/logs"],
  "ext": "js,json"
}

exec Key: Run Custom Commands

It defines what command to run when a restart is triggered. You can change the default script Nodemon runs and also the binary it uses to run that script, it can be node, babel-node, ts-node or anything else.

{
  "watch": ["src"],
  "ignore": ["src/logs"],
  "ext": "js,json",
  "exec": "node src/server.js"
}

execMap: Map File Extensions to Runtimes

It tells Nodemon which binary to use for specific file types. For JavaScript files, it defaults to node. This is especially useful when working with ts-node or babel-node.

{
  "watch": ["src"],
  "ignore": ["src/logs"],
  "ext": "js,json",
  "exec": "node src/server.js",
  "execMap": {
    "js": "node"
  }
}

env Key: Set Environment Variables

The env key sets environment variables after Nodemon starts.
This won’t affect any logic that runs before Nodemon starts. Use your npm script to set NODE_ENV before execution if needed.

{
  "watch": ["src"],
  "ignore": ["src/logs"],
  "ext": "js,json",
  "exec": "node src/server.js",
  "execMap": {
    "js": "node"
  },
  "env": {
    "PORT": "3000",
  }
}

delay Key: Prevent Multiple Restarts

This helps avoid multiple back-to-back restarts when many files change at once.

{
  "watch": ["src"],
  "ignore": ["src/logs"],
  "ext": "js,json",
  "exec": "node src/server.js",
  "execMap": {
    "js": "node"
  },
  "env": {
    "PORT": "3000",
  },
  "delay": "500ms"
}

verbose: Debug Your Config

The verbose key shows detailed logs so you can see what Nodemon is doing under the hood, what’s being watched, ignored, and executed. This makes it easier to troubleshoot your Nodemon config directly from the terminal.

{
  "watch": ["src"],
  "ignore": ["src/logs"],
  "ext": "js,json",
  "exec": "node src/server.js",
  "execMap": {
    "js": "node"
  },
  "env": {
    "PORT": "3000",
  },
  "delay": "500ms",
  "verbose": true
}

This gives you full control over your Nodemon configuration without relying solely on messy CLI flags. However, CLI flags remain useful for quick overrides and one-time settings!

Move Config to package.json

Instead of using nodemon.json, you can add a nodemonConfig section to package.json. Moving the config to package.json is as easy as pasting nodemon.json content under the nodemonConfig key in package.json.

{
  "nodemonConfig": {
    "watch": ["src"],
    "ignore": ["src/logs"]
  }
}

It is handy for smaller projects and you don’t need an extra file.

Nodemon CLI Options and Flags

Nodemon’s CLI options override file-based configs. Let’s run an example:

nodemon --watch src --ignore src/logs --ext js,json --exec "node src/server.js" --delay 500ms --verbose

This CLI command covers most key configurations from nodemon.json, but certain options like env and execMap require additional setup.

--watch is equivalent to the watch key in nodemon.json. It defines which folder to monitor and you can also use its shorthand version which is -w, so nodemon --watch is equal to nodemon -w.

--ignore does the same as ignore key. Just use multiple --ignore flags to ignore multiple folders.

nodemon --watch src --ignore src/logs --ignore src/tmp

--ext, --exec, and --delay work the same way as the ext, exec, and delay keys in nodemon.json. The shorthand version of --exec is -x, so nodemon --exec is the same as nodemon -x.

--verbose turns debug output on.

Here’s a quick summary of the most common Nodemon CLI options and their shorthand versions:

GitHub Repo

Want to test this out quickly? We’ve created a sample repo with everything in place.
Clone the repo, install dependencies, and try running Nodemon on your machine right away.

Final Thoughts

Nodemon is an incredibly useful tool for improving your Node.js development workflow, but its true power shines when you configure it properly. With nodemon.json, package.json, and CLI flags at your disposal, you can fine-tune how and when your app restarts, reduce noise from irrelevant file changes, and even inject custom logic or variables into the runtime.

Did this guide help you tidy up your Nodemon setup? Leave a comment or watch our full Nodemon config video tutorial for a hands-on walkthrough!