This article applies to Nelio A/B testing versions prior to 5.0.

If you are looking for documentation for our newest version, please bookmark

Absolutely! Nelio A/B Testing will work properly even if your WordPress site is behind a cache system or a CDN. If you want to know how, keep reading.

The challenge of caches

Cache mechanisms are a real challenge for A/B testing. When your website is behind a cache, it's possible that all your visitors end up seeing the same (original) alternative, thus making A/B testing impossible. Some A/B Testing plugins for WordPress are simply not compatible with caches and make you choose between performance and conversion optimization. Nelio A/B Testing, on the other hand, is not only compatible with caches, but it even makes use of them!

How does Nelio A/B Testing use caches?

 When loading alternative content, Nelio adds one (or more) GET parameter in the URL:


that specifies whether the original (nab=0) or an alternative version (nab=1 or nab=2) has to be loaded. Thanks to this parameter, your cache system will see different URLs depending on which alternative is being loaded and, therefore, it will cache each alternative as if they were different pages (even though some are just a variant of the former).

This "testing" parameters are added by our tracking JavaScript on the client side. You can read more about how Nelio decides when alternative content has to be loaded and how it's requested.