I recently wanted to conduct a little bit of A/B testing on a project of mine, so I went exploring – yet again – the free options.

There are lots of very good server-side solutions, but what I wanted was one that I didn’t need to configure on the server, and that could be integrated into Google Analytics, where I already track my websites performances. I found on the web some how-tos about the use of GA custom variables for A/B testing, but no ready-made libraries to do so.

So I created my own javascript library; it is so simple that I decided to implement it without any external dependencies, so that if in the future I want to use it without jQuery (which I usually use) I’ll be able to do so. And it is so simple that it was easy to give a minimum polishing and make it ready to publish, to give it back to the community.

These are the main features:

Easy to set up You just list the possible variants, the randomization is handled automatically You just mark the html elements you want to test on with a class, the substitution is automatic No need to set anything up server side, all the results are stored on Google Analytics

Consistent user experience: The selected variant is stored in a cookie, so the user will see the same one when coming back

No external dependencies: Pure javascript, you just need to include GA

Flexible: You can conduct multiple, independent experiments at the same time. Each experiment will use a custom variable slot

I’m releasing the library with an MIT license, and you can find it – with basic instructions on how to use it – on Github. Enjoy!