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NPM cncjs

A web-based interface for CNC milling controller running Grbl, Smoothieware, or TinyG. 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

Getting Started

Node.js Installation

Node.js 4 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 https://github.com/creationix/nvm.git ~/.nvm
cd ~/.nvm
git checkout `git describe --abbrev=0 --tags`
cd ..
. ~/.nvm/nvm.sh

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.sh" ] && . "$NVM_DIR/nvm.sh" # This loads nvm

Once installed, you can select Node.js versions with:

nvm install 4
nvm use 4

If you’re using Node.js 4 or earlier versions, it’s recommended that you upgrade npm to the latest version. To upgrade, run:

npm install npm@latest -g


Install cncjs as a non-root user, or the serialport module may not install correctly on some platforms like Raspberry Pi.

npm install -g cncjs

If you’re going to use sudo or root to install cncjs, you need to specify the --unsafe-perm option to run npm as the root account.

sudo npm install --unsafe-perm -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 https://cnc.js.org/docs/installation/ for other installation methods.


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


Run cnc to start the server, and visit http://yourhostname:8000/ to view the web interface. Pass --help to cnc for more options.

pi@rpi3$ 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

To troubleshoot issues, run:

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": [
      "title": "Update (root user)",
      "commands": "sudo npm install -g cncjs@latest --unsafe-perm; pkill -a -f cnc"
      "title": "Update (non-root user)",
      "commands": "npm install -g cncjs@latest; pkill -a -f cnc"
      "title": "Reboot",
      "commands": "sudo /sbin/reboot"
      "title": "Shutdown",
      "commands": "sudo /sbin/shutdown"
  "events": [],
  "macros": [],
  "users": []




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 http://jscut.org/jscut.html.


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 cheton@gmail.com.

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!



Licensed under the MIT License.