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A web-based interface for CNC milling controller running Grbl or TinyG2

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NPM cnc

A web-based interface for CNC milling controller running Grbl or TinyG2. It runs on an Raspberry Pi or a laptop computer that you have Node.js installed, connecting to the Arduino over a serial connection using a USB serial port, a Bluetooth serial module, or a Serial-to-WiFi module like XBee or USR-WIFI232-T.



Browser Support

Yes Yes Yes Not supported Yes Yes


Node.js Installation

Node.js v4 or higher is recommended. You can install Node Version Manager to manage multiple Node.js versions. If you have git installed, just clone the nvm repo, and check out the latest version:

$ git clone ~/.nvm
$ cd ~/.nvm
$ git checkout `git describe --abbrev=0 --tags`
$ cd ..
$ . ~/.nvm/
$ nvm install 4

Add these lines to your ~/.bash_profile, ~/.bashrc, or ~/.profile file to have it automatically sourced upon login:

export NVM_DIR="$HOME/.nvm"
[ -s "$NVM_DIR/" ] && . "$NVM_DIR/" # This loads nvm

If you're using Node.js v4 or earlier versions, it's recommended that you use npm v3 to install packages. To upgrade, run:

$ npm install npm@latest -g

Getting Started

Make sure you're using Node.js v4 (or higher) and npm v3:

$ nvm use 4
Now using node v4.5.0 (npm v3.10.6)

Install cncjs without sudo, or the serialport module may not install correctly on some platforms like Raspberry Pi.

$ npm install -g cncjs

It's recommended that you run Raspbian Jessie on the RPi2 or RPi3. For Raspbian Wheezy, be sure to install gcc/g++ 4.8 before npm install.

Check out wiki for other installation methods.


Run npm install -g cncjs@latest to install the latest version. To determine the version, use cnc -V.


Run cnc or ~/.npm/bin/cnc to start the server, and visit http://yourhostname:8000/ to view the web interface:

$ cnc
2016-12-01T15:00:41.499Z - info: Started the server at

Run cnc with -h for detailed usage:

$ cnc -h
  Usage: cnc [options]
    -h, --help                          output usage information
    -V, --version                       output the version number
    -p, --port                          set listen port (default: 8000)
    -l, --host                          set listen address or hostname (default:
    -b, --backlog                       set listen backlog (default: 511)
    -c, --config <filename>             set config file (default: ~/.cncrc)
    -v, --verbose                       increase the verbosity level
    -m, --mount [<url>:]<path>          set the mount point for serving static files (default: /static:static)
    -w, --watch-directory <path>        watch a directory for changes
    --access-token-lifetime <lifetime>  access token lifetime in seconds or a time span string (default: 30d)
    --allow-remote-access               allow remote access to the server
    $ cnc -vv
    $ cnc --mount /pendant:/home/pi/tinyweb
    $ cnc --watch-directory /home/pi/watch
    $ cnc --access-token-lifetime 60d  # e.g. 3600, 30m, 12h, 30d
    $ cnc --allow-remote-access

Instead of passing command line options for --watch-directory, --access-token-lifetime, and --allow-remote-access, you can create a ~/.cncrc file that contains the following configuration in JSON format:

    "watchDirectory": "/path/to/dir",
    "accessTokenLifetime": "30d",
    "allowRemoteAccess": false

If you need view detailed logs for troubleshooting, you can run the server in debug mode.

$ cnc -vvv

Configuration File

The configuration file .cncrc contains settings that are equivalent to the cnc command-line options. The configuration file is stored in user's home directory. To find out the actual location of the home directory, do the following:

  • Linux/Mac

    echo $HOME
  • Windows

    echo %USERPROFILE%

Check out an example configuration file here.

File Format

  "watchDirectory": "/path/to/dir",
  "accessTokenLifetime": "30d",
  "allowRemoteAccess": false,
  "state": {
    "checkForUpdates": true
  "commands": [
      "text": "Update (root user)",
      "command": "sudo npm install -g cncjs@latest --unsafe-perm; pkill -a -f cnc"
      "text": "Update (non-root user)",
      "command": "npm install -g cncjs@latest; pkill -a -f cnc"
      "text": "Reboot",
      "command": "sudo /sbin/reboot"
      "text": "Shutdown",
      "command": "sudo /sbin/shutdown"
  "macros": [],
  "users": []


Visit to download the latest "" file.



There are several *.gcode files in the examples directory. You can use the GCode widget to load a GCode file and make a trial run.

If you don't have a CAM software, try using jscut to create G-Code from *.svg. It's a simple CAM package that runs in the browser.

Check out a live demo at


Use GitHub issues for requests.

Pull requests welcome! Learn how to contribute.


You can help translate resource files in both of app and web directories from English to other languages. Check out Localization guide to learn how to get started. If you are not familiar with GitHub development, you can open an issue or send your translations to

Locale Language Status Contributors
cs Čeština (Czech) ✔️ Miroslav Zuzelka
de Deutsch (German) ✔️ Thorsten Godau
es Español (Spanish)
fr Français (French) ✔️ Simon Maillard, CorentinBrulé
it Italiano (Italian) ✔️ vince87
hu Magyar (Hungarian) ✔️ Sipos Péter
pt-br Português (Brasil) ✔️ cmsteinBR
ru Ру́сский (Russian) ✔️ Denis Yusupov
zh-tw 繁體中文 (Traditional Chinese) ✔️ Cheton Wu
zh-cn 简体中文 (Simplified Chinese) ✔️ Mandy Chien, Terry Lee
ja 日本語 (Japanese) ✔️ Naoki Okamoto


If you would like to support this project, you can make a donation using PayPal. Thank you!



Copyright (c) 2015-2016 Cheton Wu

Licensed under the MIT License.