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The Espruino Web IDE - A Chrome Web App for programming Espruino
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EspruinoTools @ a51a268 Added Web Serial - thanks @reillyeon! Aug 10, 2019
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extras fix issue caused by combining new JS esprima files Apr 3, 2019
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js Tweaks for better usability on mobile phones May 15, 2019
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LICENSE Initial commit Sep 26, 2013 Add Gito to Patreon list Jun 21, 2019
electron-app.js Add server initialisation options Jul 22, 2016
electron-loader.js helpful error messages Jun 18, 2016
embed.js Fix WebBLE issues Jul 12, 2018
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main.html re-order files to ensure that pretokenise works when writing to flash Sep 9, 2019
manifest.json Added Web Serial - thanks @reillyeon! Aug 10, 2019
nw-loader.js oops Oct 27, 2016
package.json Added Web Serial - thanks @reillyeon! Aug 10, 2019
server.js Added Web Bluetooth flasher Jun 20, 2018
serviceworker.js re-order files to ensure that pretokenise works when writing to flash Sep 9, 2019
upload.html Finish npm modules support removal Sep 28, 2018
webapp_manifest.json fix webapp manifest, and auto-hide toolbar if it's not needed Feb 8, 2018

Espruino Web IDE Join the chat at

A VT100 Serial Terminal as a Chrome Web App (with both syntax highlighted and graphical editors) - designed for writing code on microcontrollers that use the Espruino JavaScript interpreter. It can also run natively via Node.js and Electron, or a version with limited IO can be used as a website.

ScreenShot ScreenShot

This is a Chrome Web App (mainly) that uses chome.serial to access your PC's serial port. You can download it from the Chrome Web Store:

It implements basic VT100 terminal features (up/down/left/right/etc) - enough for you to write code using the Espruino. You can also use the right-hand pane to write JavaScript code on the PC, and can then click the 'transfer' icon to send that code directly down the Serial Port.

Version Communications Benefits
Chrome Web App USB, Serial, Audio, TCP/IP Easy to install from Chrome Web Store
Node.js App / NW.js app USB, Serial, Bluetooth Low Energy Can be run of systems without Chrome web browser
Web Version Audio, Bluetooth Low Energy (via Web Bluetooth) Just go to a URL

The development of this app is supported by purchases of official Espruino boards as well as the generous donations of my supporters on Patreon

Installing From Chrome Web Store

Installing from NPM

If you have an up to date version of Node.js and NPM, you can execute the commands:

  • On Linux, sudo apt-get install build-essential libudev-dev
  • sudo npm install nw -g
  • sudo npm install espruino-web-ide -g
  • To enable BLE support: sudo setcap cap_net_raw+eip $(eval readlink -f $(which node))
  • espruino-web-ide

Note: For command-line access you might also want to take a look at EspruinoTools

Note 2: If you're not seeing any options for devices to connect to, it might be because your nw.js and node versions don't match. If that's the case you need to manually rebuild all the 'native' modules.

npm install -g nw-gyp
# Now, for directory in node_modules with a binding.gyp file...
# target should match the nw.js version in node_modules/nw/package.json
nw-gyp rebuild --target=0.18.6 --arch=x64

Installing from GitHub (Latest Version)

You need to obtain both the EspruinoWebIDE repository and the EspruinoTools repository, a submodule used in the Web IDE. A simple way to obtain both repositories is via the git command:

git clone --recursive

This will clone both the EspruinoWebIDE repository and the submodule dependencies. Alternatively, you can download or clone both repositories individually following the steps below:

  • Download the files in EspruinoWebIDE to an EspruinoWebIDE directory on your PC (either as a ZIP File, or using git)
  • Download the files in EspruinoTools into the EspruinoWebIDE/EspruinoTools on your PC (either as a ZIP File, or using git)

Running in Chrome

  • Install and run the Chrome Web Browser
  • Click the menu icon in the top right
  • Click 'Settings'
  • Click 'Extensions' on the left
  • Click 'Load Unpackaged Extension'
  • Navigate to the EspruinoWebIDE Directory and click Ok
  • Job Done. It'll now appear as an app with the 'Unpacked' banner so you can tell it apart from the normal Web IDE. You can start it easily by clicking the 'Launch' link on the extensions page, or whenever you open a new tab.

Running in Node.js

  • Go to the EspruinoWebIDE directory
  • Run npm install
  • Run npm start

Chrome Permissions

This web app requires the following permissions:

  • Serial port access : So that it can access the Espruino board via USB/Serial
  • Webcam access : So that when you click the little person icon in the top-right of the terminal window, you can overlay the terminal on a live video feed
  • Audio access: if you want to communicate with Espruino using your headphone jack
  • Filesystem/storage access : For loading/saving your JavaScript files to your local disk


  • Run the Web app
  • Click the Help (?) icon, then the Tour button to get a guided tour.

Running with Node.js/Electron and don't see any ports when you try and connect? You're probably using a version of Node.js that doesn't match Electron. This causes NPM to load binary modules (for serialport and bleat) that are for the old version of Node and that won't work in Electron. To fix it, update Node.js, delete node_modules and run npm install again.

Debugging with NW In order to debug the WebIDE using DevTools you need to install the SDK flavor of nw. This can be done with npm install -g nw --nwjs_build_type=sdk instead of just npm install -g nw. Once the SDK flavor is installed you can specify a remote-debug port like this nw --remote-debugging-port=9222 .

Full Web Version

The Web IDE is hosted on the Espruino Website and can use Web Bluetooth to communicate with Puck.js devices. There is also a version served straight from GitHub.

Web browser permissions stop this accessing the Serial port, but it can:

Potentially it could also communicate directly with Espruino boards via WebSockets or even AJAX, but this isn't implemented yet.

Note: Sadly Apple have chosen not to implement getUserMedia on their iOS devices at the moment, so Serial over Audio won't work on iPhone/iPad/etc. (The menu item won't appear in the settings page)


Contributions are welcome - especially if they make the Web IDE easier to use for newcomers!

Getting Started

Espruino Web IDE expects the EspruinoTools repository to be in EspruinoWebIDE/EspruinoTools. If you're using Git, make sure you add it using the command:

git submodule add

Code Style

  • Please stick to a K&R style with no tabs and 2 spaces per indent
  • Filenames should start with a lowerCase letter, and different words should be capitalised, not split with underscores

Code Outline

  • Core functionality goes in js/core, Plugins go in js/plugins. See plugins/_examplePlugin.js for an example layout
  • Plugins/core need to implement in init function, which is called when the document (and settings) have loaded.
  • Plugins can respond to specific events using Espruino.addProcessor. For instance you can use Espruino.addProcessor("transformForEspruino", function (data,callback) { .. }) and can modify code before it is sent to Espruino.
  • Icons are added using Espruino.Core.App.addIcon and are generally added from JsvaScript file that performs the operation
  • Config is stored in Espruino.Config.FOO and is changed with Espruino.Config.set("FOO", value). Espruino.Core.Config.add can be used to add an option to the Settings menu.
  • Annoyingly, right now plugins still have to be loaded via a <script> tag in main.html
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