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GrblServer is a Grbl interface for standalone gcode execute service which works with nodejs.

GrblServer provides:

  • WebSocket APIs
  • Multiple session for one Grbl (broadcast Grbl state to all clients) This is useful for show state in multiple view (eg. local LCD and remote browsers)


Standalone WebApp

By "Add to Home screen" feature on Chrome for Android.

Responsive View

Install & Basic Usage

You must install node.js and git.

Clone repository to local

git clone

Install dependencies

cd GrblServer
npm install


Create config/local.json. You must edit "serialPort" path.

cp config/default.json config/local.json
vi config/local.json

Run GrblServer

You should connect Grbl installed Arduino before running.

node bin/grbl-server.js

Open client by browser

Google Chrome is recommended for performance.

open http://localhost:8080/

(GrblServer also serves static files under ./browser)



Specify WebSocket/HTTP server port to serve.


Specify serial port path which is connected to Grbl.


Specify serial baudrate to Grbl.

You want to write configuration with other formats? You can:


Specify TLS key/cert for HTTP2. Default is empty (disabled).

GrblServer includes localhost cert (self signed certificates). Use it by following:

"TLSKey" : "dev/server.key",
"TLSCert" : "dev/server.crt" 

Or create self signed certificates by dev/


Jogging by smartphone's browser

with Raspberry Pi


Ensure that NodeJS has been installed on the Rapsberry Pi (

Clone GrblServer on Raspberry Pi:

mkdir app
cd app
git clone
cd GrblServer
npm install
vi config/local.json

Edit /etc/inittab to auto login by user pi:

sudo vi /etc/inittab

# comment out following line:
# 1:2345:respawn:/sbin/getty --noclear 38400 tty1 
# and add following line:
1:2345:respawn:/bin/login -f pi tty1 </dev/tty1 >/dev/tty1 2>&1

Edit /etc/rc.local to auto launch GrblServer:

sudo vi /etc/rc.local
# add following line before exit
sudo -u pi /home/pi/app/GrblServer/service/


GrblServer is written in TypeScript.

sudo npm install -g typescript
npm install
make watch # tsc watch
make server # launch websocket/http server

browser client is written JavaScript with Polymer

Above make server also serves static files under browser/.

Grbl for development

You may need actual connection to Grbl. But you should not connect to Grbl which connected to powered CNC machine. So I suggest you to make another Grbl installed Arduino and use it for development.

Grbl is open-loop control except homing and probing. It means you don't need to connect actual CNC machine in most case.


Send pull-request.