Track user interactions without JavaScript
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Analyze user interactions via CSS, without JavaScript on client-side. Demo at

  • Why?
  • Because we can

How it works

As you probably know, in css we can add external resources via url(resource) property. Usually, this resource is only loaded when its needed. So, we can create HTML/CSS that will track user interactions, and send request to our backend.

This library was created in order to simplify the creation of tracking css.

How to use

First, install library with composer:

composer require bogdaan/spycss

For example, you want to track click on some link. We can use this snippet to generates CSS and HTML for you link inside view:

// inside controller or DI:
$userId = 'get_from_cookie--OR--fetch_from_db';
$backendUrl = 'https://spy-css-backend/';
$s = new \SpyCss\SpyCss($userId, $backendUrl);

// inside you view, generates element:
// <a class="scsssXXXX" href="">Novikov Bogdan</a>
echo $s->builder()
    ->content('Novikov Bogdan')
    ->attribute('href', '')
        new \SpyCss\Interaction\Active('click_on_hcbogdan_com')

// generates special styles like:
// .scsssXXXX:active::after {content: url(https://spy-css-backend/userId/active/click_on_hcbogdan_com);}'
echo '<style>'.$s->extractStyles().'</style>';

You can create keylogger for input type="text" fields (snippet at jsfiddle):

// ... init SpyCss

// set alphabet
$logThisChars = 'abcdefgABCDEFG';

// create input field
echo $s->builder()
    ->attribute('name', 'field')
        new \SpyCss\Interaction\Keylogger($logThisChars)

// generates special styles
echo '<style>'.$s->extractStyles().'</style>';

See more examples at spycss-demo

Directory structure

├── Builder.php          # Tag builder with fluent interface
├── Interaction          #
│   ├── Active.php       # Track :active state
│   ├── Checked.php      # Track :checked state on input and option
│   ├── Focus.php        # Track :focus state
│   ├── Hover.php        # Track :hover state
│   ├── Keylogger.php    # Track key press on text fields
│   ├── Online.php       # Online tracking
│   ├── Pseudo.php       #
│   └── Valid.php        # Track :valid state
├── Interaction.php      # Base class for interactions
├── SpyCss.php           #
└── Util                 #
    └── Html.php         # Html tag helpers


  • Review browser support
  • Update demo
  • Add more interactions
  • Implement twig helper

Read more


Pull request are welcome.

Inspired by jbtronics/CrookedStyleSheets.