A/B testing framework
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Abba is a simple a/b testing self-hosted framework built to help improve conversion rates on your site.

  • Simple JavaScript API
  • Multi variant support
  • Filter results by date and browser




  • Ruby 1.9.3
  • Mongo

The default username and password are guard / llama. Change these in config.yml, unless you want everybody to access your test results. SSL is required in an production environment by default.

To run locally:

bundle install
thin start

Heroku 10 seconds setup

git clone git://github.com/stripe/abba.git && cd abba
heroku create
heroku addons:add mongohq:sandbox
git push heroku master
heroku open

The default username and password are guard / llama.

A/B testing API

First include abba.js using a script tag. The host of this url will need to point to wherever you deployed the app.

<script src="//localhost:4050/v1/abba.js"></script>

Then call Abba(), passing in a test name and set up the control test and variants.

  Abba('test name')
    .control('test a', function(){ /* ... */ })
    .variant('test b', function(){ /* ... */ })

The control is whatever you're testing against, and is usually the original page. You should only have one control (and the callback can be omitted).

The variants are the variations on the control that you hope will improve conversion. You can specify multiple variants. They require a variant name, and a callback function.

When you call start() Abba will randomly execute the control or variants' callbacks, and record the results server side.

Once the user has successfully completed the experiment, say paid and navigated to a receipt page, you need to complete the test. You can do this by invoking complete().

  // On successful conversion
  Abba('test name').complete();

TLDR example

<script src="//my-abba.herokuapp.com/v1/abba.js"></script>

    .variant('Text: Complete Purchase', function(){
      $('form button').text('Complete Purchase');
    .variant('Color: green', function(){
      $('form button').css({background: 'green'});

You can find a more complete example under ./public/test.


Persisting results

If set the persist option to true, then the experiment won't be reset once it has completed. In other words, that visitor will always see that particular variant, and no more results will be recorded for that visitor.

  Abba('Pricing', {persist: true}).complete();


You can set a variant weight, so some variants are used more than others:

Abba('My Checkout')
  .control('Control', {weight: 20})
  .variant('Variant 1', {weight: 3}, function(){
    $('#test').text('Variant 1 was chosen!');
  .variant('Variant 2', {weight: 3}, function(){
    $('#test').text('Variant 2 was chosen!');

In the case above, the Control will be invoked 20 times more often than the other variants.

Flow control

You can continue a previously started test using continue().

Abba('My Checkout')
  .variant('Variant 1', function(){
    $('#test').text('Variant 1 was chosen!');
  .variant('Variant 2', function(){
    $('#test').text('Variant 2 was chosen!');

Nothing will be recorded if you call continue() instead of start(). If a variant hasn't been chosen previously, nothing will be executed.

You can reset tests using reset().

Abba('My Checkout').reset();

Lastly, you can calculate the test that you want to run server side, and just tell the JavaScript library which flow was chosen.

Abba('My Checkout').start('Variant A')


If you're triggering the completion of a test on a link click or a form submit, then things get a bit more complicated.

You need to ensure that tracking request doesn't get lost (which can happen in some browsers if you request an image at the same time as navigating). If the link is navigating to an external page which you don't control, then you have no choice but to cancel the link's default event, wait a few milliseconds, then navigate manually:

  $('body').on('click', 'a.external', function(e){
    // Prevent navigation
    var href = $(this).attr('href');

    Abba('My Links').complete();

      window.location = href;
    }, 400);

That's far from ideal though, and it's much better to place the tracking code on the page you're going to navigate to. If you have control over the page, then add the following code that checks the URL's hash.

  if (window.location.hash.indexOf('_abbaTestComplete') != -1) {
    Abba('My Links').complete();

Then add the hash to the link's URL:

<a href="/blog#_abbaTestComplete">


Thanks to the following projects: