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Lukas Bachschwell 0587918621
Merge pull request #109 from A-damW/master
6 months ago
.github/ISSUE_TEMPLATE Update issue templates 3 years ago
data slider sends (browser dependent) lots of events, throttle using only unique values. 6 months ago
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examples Fix prepare fs example 10 months ago
img/blocks new file: ESPUI_blocks.js 4 years ago
lang Closes #74 Adds chinese facilino translation 1 year ago
src slider sends (browser dependent) lots of events, throttle using only unique values. 6 months ago
tools Moved examples/gui/data to data/ and adjusted tools/*.py 2 years ago
.clang-format Use DEBUG_ESPUI to en/disable debug code from being compiled 10 months ago
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ESPUI_blocks.js modified: ESPUI_blocks.js 4 years ago
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library.json Version 2.0.2 10 months ago
library.properties Version 2.0.2 10 months ago




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.

The Library runs fine on any kind of ESP8266 and ESP32 (NodeMCU Boards, usw)

Changelog for 2.0:

  • ArduinoJSON 6.10.0 Support
  • split pad into pad and padWithCenter
  • Cleaned Order or parameters on switch
  • cleaned Order of parameters on pad
  • Changes all numbers to actually be numbers (slider value, number value, min and max)

Added features

Further Roadmap

  • Slider css issues
  • implement Gauge
  • File upload ?


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

How to Install

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

Just include this library as a dependency on lib_deps like so:

lib_deps =
    ESPAsyncTCP # or AsyncTCP on ESP32

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

Manual Install Arduino IDE

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}

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 web interface. 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!

OPTIONAL: 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 do 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 strings that are already saved in the chip's filesystem and you have more program memory to work with.

User interface Elements

  • Label
  • Button
  • Switch
  • Control pad
  • Control pad with center button
  • Slider
  • Text Input
  • Numberinput
  • Graph
  • Option select

Checkout the example for the usage or see the detailed info below

Available colors:

  • Turquoise
  • Emerald
  • Peterriver
  • Wetasphalt
  • Sunflower
  • Carrot
  • Alizarin
  • Dark
  • None

(Use like ControlColor::Sunflower)


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 ESP and the client browser works using web sockets. ESPUI does not need network access and can be used in standalone access point mode, all resources are loaded directly from the ESPs memory.

This section will explain in detail how the Library is to be used from the Arduino code side. 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(Control *sender, int value) 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 (B_DOWN) and one for release (B_UP).

  • B_DOWN
  • B_UP



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 when turning on (S_ACTIVE) and one when turning off (S_INACTIVE).



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.

  • P_FOR_UP



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. In the Callback the slider does not return an int but a String. Use the .toInt function to convert the value, see the gui example to check how it works.

A slider usually only sends a new value when it is released to save the esps from being spammed with values. This behaviour can be cahnged globally using a property of the ESPUI object before begin():

  ESPUI.sliderContinuous = true;
  ESPUI.begin("ESPUI Control");

Number Input


The numberinput can be used to directly input numbers to your program. You can enter a Value into it and when you are done with your change it is sent to the ESP.

A number box needs to have a min and a max value. To set it up just use:

ESPUI.number("Numbertest", &numberCall, ControlColor::Alizarin, 5, 0, 10);

Text Input


The textinput works very similar like the number input but with a string. You can enter a String into it and when you are done with your change it is sent to the ESP.



The graph widget can display graph points with timestamp at wich they arrive

Use ESPUI.addGraphPoint(graphId, random(1, 50)); to add a new value at the current time, use ESPUI.clearGraph(graphId) to clear the entire graph. Graph points are saved in the browser in localstorage to be persistant, clear local storageto remove the points or use clearGraph() from a bbutton callback to provide a clear button.

Option select

option1 option2

The option select works by first creating a select widget like so

uint16_t select1 = ESPUI.addControl( ControlType::Select, "Select:", "", ControlColor::Alizarin, tab1, &selectExample );

And then adding Options to it like seperate widgets, specifying the select as the parent:

ESPUI.addControl( ControlType::Option, "Option1", "Opt1", ControlColor::Alizarin, select1 );
ESPUI.addControl( ControlType::Option, "Option2", "Opt2", ControlColor::Alizarin, select1 );
ESPUI.addControl( ControlType::Option, "Option3", "Opt3", ControlColor::Alizarin, select1 );

Check the tabbedGui example for a working demo

Using Tabs


Tabs can be used to organize your widgets in pages. Check the tabbedGui example. Tabs can be created using the generic functions like so: ESPUI.addControl( ControlType::Tab, "Settings 1", "Settings 1" );

Then all widgets for the tab need to be added to it by specifying the tab as the parrent (widgets not added to a tab will be shown above the tab selctor)

ESPUI.addControl( ControlType::Text, "Text Title:", "a Text Field", ControlColor::Alizarin, tab1, &textCall );

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 gui.ino example). The web interface can then be used from multiple devices at once and also shows an connection status in the top bar.

Advanced: Generic creation and updates of control widgets

There are 2 generic functions to create and update controls, to see them in action check the gui-generic-api example.

To create a generic control use: uint16_t switchOne = ESPUI.addControl(ControlType::Switcher, "Switch one", "", ControlColor::Alizarin, Control::noParent, &switchExample);

Then its value can be updated by doing:

ESPUI.updateControlValue(status, "Start");

You can also update other parameters of the control like its color using:

    ESPUI.getControl(switchOne)->color = ControlColor::Carrot;

Log output

ESPUI has several different log levels. You can set them using the ESPUI.setVerbosity(Verbosity::VerboseJSON) function.

Loglevels are:

  • Verbosity::Quiet (default)
  • Verbosity::Verbose
  • Verbosity::VerboseJSON

VerboseJSON outputs the most debug information.

Advanced properties

If you have many different widgets it might be necessary to adjust the JSON Buffers used internally in ESPUI before .begin() :

 ESPUI.jsonUpdateDocumentSize = 2000; // This is the default, and this value is not affected by the amount of widgets
 ESPUI.jsonInitialDocumentSize = 8000; // This is the default, adjust when you have too many widgets or options
 ESPUI.begin("ESPUI Control");

Notes for Development

If you want to work on the HTML/CSS/JS files, do make changes in the 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 and b) the C header files in src that contain the minified and gzipped HTML/CSS/JS data. Alternatively, you can specify the --source and --target arguments to the prepare_static_ui_sources.py script (run the script without arguments for help) if you want to use different locations.

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. (Do NOT commit all the minified versions for the non changed files)


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

Otherwise I really welcome Pull Requests.