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Lukas Bachschwell c5c6e37dfb
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ESPUI is a simple library to make a web user interface for your projects using the ESP8266 or the ESP32 It uses web sockets and lets you create, control, and update elements on your GUI through multiple devices like phones and tablets.

ESPUI uses simple Arduino-style syntax for creating a solid, functioning user interface without too much boilerplate code.

So if you either don’t know how or just don’t want to waste time: this is your simple solution user interface without the need of internet connectivity or any additional servers.

I completely rewrote the EasyUI Library created by ayushsharma82 Here Now it uses ESPAsyncWebserver and is mainly to be used with the ESP32 Processor.

Important notes

Currently ESPUI only supports ArduinoJSON 5.x, please keep that in mind! Version 6 support is work in progress


This library is dependent on the following libraries to function properly.

Plus for ESP8266

Additionally necessary for ESP32

How to Install

Make sure all the dependencies are installed, then install like so:

You can find this Library in the Arduino IDE library manager Go to Sketch > Include Library > Library Manager > Search for “ESPUI” > Install

Manual Install

For Windows: Download the Repository and extract the .zip in Documents>Arduino>Libraries>{Place “ESPUI” folder Here}

For Linux: Download the Repository and extract the .zip in Sketchbook/Libraries/{Place “ESPUI” folder Here}

For macOs: Download the Repository and extract the .zip in ~/Documents/Arduino/libraries/{Place “ESPUI” folder Here}

Manually through IDE

Download the Repository, Go to Sketch>Include Library>Add .zip Library> Select the Downloaded .zip File.

Getting started

ESPUI serves several files to the browser to build up its webinterface. This can be achieved in 2 ways: PROGMEM or SPIFFS

When ESPUI.begin() is called the default is serving files from Memory and ESPUI should work out of the box!

But if this causes your program to use too much memory you can burn the files into the SPIFFS filesystem on the ESP. There are now two ways to do this: you can either use the ESP file upload tool or you use the library function ESPUI.prepareFileSystem()

Just open the example sketch prepareFileSystem and run it on the ESP, (give it up to 30 seconds, you can see the status on the Serial Monitor), The library will create all needed files. Congratulations, you are done, from now on you just need to to this again when there is a library update, or when you want to use another chip :-) Now you can upload your normal sketch, when you do not call the ESPUI.prepareFileSystem() function the compiler will strip out all the unnecessary that is already saved in the chip’s filesystem and you have more programm memory to work with.

Manual way (mainly for development)

To do this download and install me-no-devs wonderful ESP32 sketch data uploader or for ESP8266 ESP8266 sketch data uploader

Then open the gui example sketch and select “Upload Sketch Data” from the Tools menu for your processor. Now you are set to go and use any code you want to with this library

User interface Elements

  • Label (updateable)
  • Button
  • Switch (updateable)
  • Control pad
  • Control pad with center button
  • Slider
  • Text Input (updateable)
  • Numberinput (updateable)

Checkout the example for the usage

Available colors:


Roadmap :

  • Setup SPIFFS using values in program memory
  • ESP8266 support
  • PlattformIO Integration
  • Multiline Labels
  • GZip Files and serve from memory
  • Datagraph output -> WIP
  • ~~Number input ~~
  • ~~Text input ~~
  • Dokumentation for Text and number widget
  • Number min and max value
  • proper return value (as int and not as string) for slider
  • Maybe a slider range setting, meanwhile please use map()


The heart of ESPUI is ESPAsyncWebserver. ESPUI’s frontend is based on Skeleton CSS and jQuery-like lightweight zepto.js for Handling Click Events Etc. The communication between the ESP32 and the client browser works using web sockets. ESPUI does not need network access and can be used in standalone access point mode. All assets are loaded from the internal SPIFFS filesystem of the ESP32.

This section will explain in detail how the Library is to be used from the Arduino code side. As of now the Facilino blocks are not implemented. In the arduino setup() routine the interface can be customised by adding UI Elements. This is done by calling the corresponding library methods on the Library object ESPUI. Eg: ESPUI.button(“button”, &myCallback); creates a button in the interface that calls the “myCallback” function when changed. All buttons and items call their callback whenever there is a state change from them. This means the button will call the callback when it is pressed and also again when it is released. To separate different events an integer number with the event name is passed to the callback function that can be handled in a switch(){}case{} statement. Here is an overview of the currently implemented different elements of the UI library:



Buttons have a name and a callback value. They have one event for press and one for release.



Switches sync their state on all connected devices. This means when you change their value they change visibly on all tablets or computers that currently display the interface. They also have two types of events: one for turning on and one for turning off.


control pads

Button pads come in two flavours: with or without a center button. They are very useful for con-trolling all kinds of movements of vehicles or also of course our walking robots. They use a single callback per pad and have 8 or 10 different event types to differentiate the button actions.



Labels are a nice tool to get information from the robot to the user interface. This can be done to show states, values of sensors and configuration parameters. To send data from the code use ESP.print(labelId, “Text”); . Labels get a name on creation and a initial value. The name is not changeable once the UI initialised.

Labels automatically wrap your text. If you want them to have multiple lines use the normal <br> tag in the string you print to the label



The Slider can be used to slide through a value from 1 to 100. Slides provide realtime data, are touch compatible and can be used to for example control a Servo. The current value is shown while the slider is dragged in a little bubble over the handle.

Initialisation of the UI

After all the elements are configured you can use ESPUI.begin(“Some Title”); to start the UI interface. (Or ESPUI.beginSPIFFS(“Some Title”); respectively) Make sure you setup a working network connection or AccesPoint before (See example). The web interface can then be used from multiple devices at once and also shows an connection status in the top bar. The library is designed to be easy to use and can still be extended with a lot of more functionality.

Notes for Development

If you want to work on the HTML/CSS/JS files, do make changes in the examples/gui/data directory. When you need to transfer that code to the ESP, run tools/prepare_static_ui_sources.py -a (this script needs python3 with the modules htmlmin, jsmin and csscompressor). This will generate a) minified files next to the original files to be uploaded with the ESP32 sketch data uploader mentioned above and b) the C header files in src that contain the minified and gzipped HTML/CSS/JS data (which are used by the prepareFileSystem example sketch or when they are served from PROGMEM; see above in the section “Getting started”). Alternatively, you can duplicate the examples/gui directory and work on the copy. Then specify the --source and --target arguments to the prepare_static_ui_sources.py script (run the script without arguments for help).

If you don’t have a python environment, you need to minify and gzip the HTML/CSS/JS files manually. I wrote a little useful jsfiddle for this, see here.

If you change something in HTML/CSS/JS and want to create a pull request, please do include the minified versions and corresponding C header files in your commits.


Liked this Library? You can support me by sending me a :coffee: Coffee.