Nelio AB Testing


Nelio A/B Testing is the most powerful and versatile conversion optimization service for WordPress. It helps you define, manage, and keep track of A/B-testing experiments, combined with powerful and beautiful Heatmaps. Nelio’s also compatible with WooCommerce. In particular, you can test alternative names, featured images, and descriptions for your products, and use your orders as conversion actions (so that you can make sure that a certain product has been purchased).

Get everything you need from within your WordPress dashboard, where you’ll benefit from a lovely, integrated, and familiar user experience.

The Most Powerful A/B Testing Solution for WordPress
Improve your landing pages, write better posts, create alternative pages, go beyond simple title testing and start testing headlines, try new themes, test different menus, modify your CSS rules, test custom post types, and test alternative widgets! Moreover, we designed Nelio A/B Testing to be compatible with your most beloved WordPress plugins such as, for instance, OptimizePress, Gravity Forms, or Contact Form 7.

Designed as a Service
Our plugin lifts all the processing load from your own server and takes it back to our cloud. This way, A/B tests do not slow down your site or interfere with your hosting provider limits. In addition, in our opinion services guarantee an amazing support, because we have to earn your trust day by day!

Our plugin comes with an easy-to-setup free trial. Just download the plugin, start your Free Trial, and discover what Nelio can offer you. Once the free-trial is over, simply subscribe to one of our plans and get an account to keep improving your WordPress site!

Reasons for choosing Nelio

Take a look at the following reasons for choosing Nelio A/B Testing!

#1 – Native A/B Testing Solution for WordPress

There’s no need to learn an external tool. Define, manage, and track the progress of your experiments directly from within WordPress. Nelio A/B Testing provides a lovely and well-known user interface that simplifies the process of creating alternatives and applying the winning ones.

#2 – Create Alternative Content for your Pages, Posts, and Custom Post Types

When creating A/B experiments, the first things you’ll want to test are the pages of your website. Does this button work? Do my visitors go from the landing page to my pricing page? What if I change this background image? Nelio A/B Testing makes page (and post) experiments super easy!

Moreover, version 4.1 includes support for custom post types. Use Nelio A/B Testing with any plugin that defines its own custom post types (such as Products, Videos, Reviews, and more).

#3 – Go beyond simple title tests—Test Headlines!

Are you a Publisher? Are you an avid blogger? Then, you probably want to deliver to every reader a more engaging and relevant reading experience. Nelio A/B Testing includes is the first A/B testing tool for WordPress that offers Headline Experiments. Given a post in your site, create alternative titles, excerpts, and featured images, and discover which combination gets more visitors to click the link and further read the post from anywhere in your site!

#4 – Test Widgets

Nelio A/B Testing is the only solution that includes Menu and Widget Testing. Use the WordPress’ default user interface for creating new menus and widget sets. You’ll be able to duplicate your current menus and widgets, and modify them with just a few clicks. Discover which combination improves your conversion rate!

#5 – Beautiful Heatmaps and Click-maps

Heatmaps (and Click-maps) offer valuable information about what your visitors do and don’t do when they land to your website. Also, they are a perfect companion of A/B experiments, for they give insights on what to text next and help you understand the progress of your experiments.

#6 – Test Alternative Themes and CSS

If you’re planning to change your theme, or tweak its CSS rules, make sure they’ll benefit your business. Nelio A/B Testing makes theme and CSS testing extremely easy! Simply select the themes you want to test (or define the alternative CSS rules you want to apply), and the plugin will take care of the rest.

#7 – Conversion Actions and Evolution of Your Experiments

With Nelio A/B Testing, you can track the important actions your visitors take. Don’t get lost with tons of irrelevant options and data. Focus on what matters. Our plugin will offer you fresh information about the evolution of the experiment, with nice graphics about visitors and conversions.

#8 – Cache Support and Server Load

One of our priorities is efficiency. The process of A/B testing a site is not necessarily at odds with performance. Nelio A/B Testing implements several mechanisms to reduce the impact of testing your site, such as support for cache systems in WordPress and optional site-wide consistency (if you’re testing a page or post, not only that page or post has to change, but also any page that includes a widget referencing it).

#9 – Outstanding Support

We work very hard to offer an amazing support to all our customers. If you encounter compatibility issues or you have problems setting the plugin up and running, contact us and we’ll do our best to help you!

#10 – Subscription Plans that Fit Your Needs

Nelio A/B Testing aims to offer a complete A/B testing experience for everybody. That’s why you can create an unlimited number of experiments of any kind subscribing to any of our packages. Just check our subscription plans and select the one that better suits your needs.

As Featured On…

If you’re not convinced yet, take a look at what others say about Nelio A/B Testing.


  • Welcome Message. After installing the plugin you'll be able to either start a new free trial or configure your Nelio account.
  • Free Trial Actions. During your Free Trial, you can get more quota by simply completing the actions we offer you. Tell us a little bit more about your and your site, tweet about Nelio, or recommend us to your friends!
  • Relevant info with a quick glance. Running experiments are visible in Nelio's Dashboard. There, you'll find a summary of all the relevant information you need.
  • Progress of your Experiment. Whilst an experiment is running (or once it is finished), you can see how it is performing in the Results of the Experiment page.
  • Data made easy. Additional graphics help you understand what is going on.
  • Experiment Management. Manage your experiments without leaving WordPress: creation, deletion, and monitoring!
  • Experiment Creation. Creating new experiments has never been so easy! Just set a name, a description, and the page you want to test!
  • Alternatives are Regular Pages. For each page to test, you can create alternatives quickly and easily, from scratch or from already-existing pages!
  • Account details. View your account information and access your directly from the plugin.
  • Use our plugin in more than one site. You can use our plugin and service on more than one site. Very useful for staging and production environments!
  • Different types of experiments. Our product lets you test different aspects of your WordPress site; just select what you want to test and create the experiment!
  • Heatmaps. Our service lets you analyse the hottest areas of any page on your site so that you can understand your customers better.


About Nelio’s Free Trial

Nelio A/B Testing includes an unlimited* Free Trial. During the Free Trial, you’ll be able to run all the experiments you want and benefit from our personalized support. In order to start the Free Trial, simply install the plugin (as described below) and click on the Start Free Trial button (see the Welcome screenshot).

After the Free Trial is over, you’ll need an account to continue using Nelio A/B Testing. Simply subscribe to our service and we’ll send you an e-mail with your account information.

* The Free Trial includes up to 1,000 page views.

Installation through the WordPress Dashboard

  1. Login to your WordPress admin.
  2. Click on the plugins tab.
  3. Click the Add New button.
  4. Search for “Nelio AB Testing” or “AB Testing”
  5. Look for our plugin, click “Install Now” and then “Activate”.
  6. Once the plugin is installed and active, you can either start a new free trial or you can configure your Nelio account.

That’s it! You may now head to the new menu item on the left labeled “Nelio A/B Testing”.

Alternative installation methods

  1. Download this plugin.
  2. Login to your WordPress admin.
  3. Click on the plugins tab.
  4. Click the Add New button.
  5. Click the Upload button.
  6. Click “Install Now” and then “Activate”.
  7. Once the plugin is installed and active, you can either start a new free trial or you can configure your Nelio account.

I successfully installed the plugin. What should I do now?

If you have successfully installed our plugin using one of the aforementioned methods, now it is just time to use it! Take a look at our Getting Started Guide to cover the basics.


Why should I use an A/B Testing Solution specifically designed for WordPress?
  • Smooth learning curve. There is no need to learn yet another tool.
    Everything (from the creation of tests to the visualization of the results) is done from the WordPress dashboard you are familiar with, resulting in a well-known, perfectly integrated user interface.
  • Evolve your WordPress site easily. A native WordPress solution automates and simplifies the evolution of your site. Consider, for example, applying the winner alternative in your site as soon as the results are statistically significant. With a native solution, this is as easy as clicking one single button. With a generic tool, on the other hand, you would have to manually modify the page so that it integrates the changes you created in the (winning) alternative.
  • Fine-grained testing. The “testing unit” in a generic tool is the web page, since the HTML of the page is the only thing those tools have access to. A native WordPress solution, however, permits you to test any WordPress specific component, such as posts, pages, CSS, themes, child themes, and many more coming!
More questions? Take a look at our site!

We keep an up-to-date Knowledge Base with FAQs, Troubleshooting, compatibility discussions, and more!


November 8, 2018
I have 2 relatively small sites and it was suggested to me by Dom Wells at HPD that I try A/B testing now that I've got sufficient traffic. I'm a beginner with A/B testing and found Nelio. I have to say I'm glad I did. (Side note: Nelio allows you to use 2 of the $29 plans if the more expensive plan is a bit much for you.) I learned some interesting things, and found out some of the changes I made actually LOWERED my click through rates, rather than improving them! That kind of data is excellent. Data is displayed well, and making an alternate test page was much easier than I expected. For small changes you can have a test running in below 1 minute. I've had some technical issues pop up (as often happens with WordPress) and support has been great. Someone wrote: "Other a/b testing software have more features (like user recording sessions) and costs the same or less, but they’re not native to WordPress, so I feel like I’d have to re-create the design in my WordPress site if it performed better to make it match my theme." I don't agree at all. From what I saw, most services are more expensive. (I have no idea that that 2nd sentence was for also, as that's not really the case regardless.) Overall a very good testing plugin with great support and it's affordable. Thanks!
March 24, 2018
This is the only native wordpress A/B testing software that I know of that also tests navigation. That being said, there's a bug in the program that doesn't allow me to test my navigation. I've contacted support but I get 24-48 hours lag in response. There was another bug a week ago that wouldn't allow me to see my other goals. Other a/b testing software have more features (like user recording sessions) and costs the same or less, but they're not native to WordPress, so I feel like I'd have to re-create the design in my WordPress site if it performed better to make it match my theme. Also, I don't know how you'd test navigation elements. Still searching for A/B testing software out there that might perform better than this one.
April 21, 2017
This tool has everything you need to conduct very sophisticated testing and optimization of landing pages. It even has a very cool heatmap feature and essentially replaces 3 different tools we use to optimize the website. Highly recommended
Read all 33 reviews

Contributors & Developers

“Nelio AB Testing” is open source software. The following people have contributed to this plugin.


“Nelio AB Testing” has been translated into 1 locale. Thank you to the translators for their contributions.

Translate “Nelio AB Testing” into your language.

Interested in development?

Browse the code, check out the SVN repository, or subscribe to the development log by RSS.

Change log

4.7.8 (October 17, 2019)

  • Bug Fix. Initializing variable $nelioab_controller properly everywhere.
  • Bug Fix. Loading original and alternative widgets properly, even if there’s a third-party plugin removing widgets dynamically.
  • Improvement. Added filter to use a single cookie for experiment assignation: nelio_ab_testing_use_single_cookie. Also, there’s a second filter to determine how many possible variations should be created: nelio_ab_testing_single_cookie_max_value.
  • Improvement. Added filter nelio_ab_testing_show_alternative_posts to unhide alternative posts, pages, etc. in the WordPress Dashboard.
  • Improvement. Experiment list now includes an option to resynch exps with the cloud if something went wrong.
  • Removed i18n translations from the plugin (as it’s now managed by itself).

4.7.6 (June 26, 2019)

  • Bug Fix. Synching WooCommerce sales properly.

4.7.5 (June 5, 2019)

  • Bug Fix. Initializing variable $nelioab_controller properly, so that it doesn’t trigger a Fatal Error.

4.7.4 (June 3, 2019)

  • Bug Fix. Making sure that the account page is accessible when the account has been deactivated.
  • Bug Fix. Fixed a couple of warning from the source code.
  • Bug Fix. Fixed a fatal error when a global variable is null and we try to access one of its methods.
  • Improvement. Count product variations as a conversion too.

4.7.3 (January 31, 2019)

  • Bug Fix. Sometimes, WordPress’ autosave feature didn’t work because our plugin was adding a script into AJAX requests. This has now been fixed.

4.7.2 (December 19, 2018)

  • Bug Fix. The plugin wasn’t able to properly track conversions in Headline experiments (all variations reported the same results). This has now been fixed. Unfortunately, already-existing experiments will have to be stopped and relaunched.

4.7.1 (December 7, 2018)

  • Bug Fix. Some buttons in Gutenberg must be hidden when editing alternative content. Version 4.7.0, however, hides them always. This should not happen and this version makes sure the buttons are only hidden when editing alternative content.

4.7.0 (December 6, 2018)

  • Improvement. Following the release of WordPress 5.0, this version of Nelio A/B Testing adds basic support to Gutenberg.

4.6.23 (November 5, 2018)

  • Bug Fix. There was a bug when trimming UTF8 strings. This has now been fixed by using mb_strlen and mb_strimwidth functions.

4.6.22 (October 9, 2018)

  • Improvement. Search posts, pages, and custom post types using their ID.

4.6.21 (September 27, 2018)

  • Bug Fix. There was an error when exporting the results of the experiment in CSV format. This has now been fixed.

4.6.20 (September 3, 2018)

  • Bug Fix. Some heatmap experiments couldn’t be started because, apparently, “the tested element wasn’t published” even though this statament didn’t make any sense for that element (e.g. your latest posts). This has now been fixed.
  • Bug Fix. Order completed tracking didn’t work as expected. This has now been fixed.

4.6.19 (July 23, 2018)

  • Improvement. Added a new filter nelio_ab_testing_heatmap_url. Using this filter, you can change the URL of the page on which a heatmap will be printed. Especially useful when cross-site origin errors appear (when WordPress is behind multiple domains with redirections).
  • Bug Fix. Sometimes, when viewing a heatmap, the plugin triggered a redirection to a URL such as https://https//. This has now been fixed.

4.6.18 (May 24, 2018)

  • Bug Fix. Loading feeds from Nelio’s blog properly.

4.6.17 (May 23, 2018)

  • Update. Added a Privacy Policy suggestion for Nelio A/B Testing in WordPress’ Privacy Policy Guide.
  • Update. Modified our welcome screen to make it comply to EU’s GDPR.
  • Update. Updated links to our website.
  • Update. Added PHP required version.

4.6.16 (May 9, 2018)

  • Bug Fix. The product under test in a WooCommerce Product Summary Experiments wasn’t properly stored and, therefore, said product couldn’t be actually tested. This has now been fixed.
  • Bug Fix. There was a PHP warning due to an object not being properly initialized. This has now been fixed.
  • Bug Fix. Alternative widgets weren’t properly loaded in the front-end. This has now been fixed.
  • Bug Fix. Some form submission events weren’t tracked. This has now been fixed.
  • Improvement. Product image preview wasn’t properly shown whilst creating WooCommerce Product Summary Alternatives. This has now been fixed.

4.6.15 (April 12, 2018)

  • Bug Fix. You can now edit alternative menus in a menu experiment.
  • Bug Fix. In page/post/custom post type experiments, the checkbox for hiding the original discussion (if any) works as expected.
  • Bug Fix. When using the Salient theme, users couldn’t successfully create Menu experiments. This has now been fixed.
  • Bug Fix. Duplicating widgets in a widget experiments didn’t work. This has now been fixed.

4.6.14 (March 23, 2018)

  • Bug Fix. Free trial tasks couldn’t be completed, because Name and E-Mail couldn’t be shared. This has now been fixed.
  • Bug Fix. There was a javascript error in the results of the experiment that prevented the page from being loaded.

4.6.11 (March 21, 2018)

  • Bug Fix. Goal selector in experiment progress screen didn’t work. This has now been fixed.
  • Bug Fix. Loading a class that was missing in experiments manager.
  • Bug Fix. An HTML text in the account page was (incorrectly) escaped and its links couldn’t be clicked. This has now been fixed.
  • Bug Fix. Loading post status for alternative content properly.

4.6.10 (March 8, 2018)

  • Bug Fix. In the screen for creating menu experiments, the button New Alternative Menu (based on an existing one) didn’t work. This has now been fixed.

4.6.9 (March 3, 2018)

  • Improvement. Using WordPress’ HTTP API instead of cURL in iesupport.php (which was a workaround for old IE browsers).
  • Improvement. Removed welcome page, because it sometimes failed due to object caches not clearing transients.
  • Improvement. Sanitazing and escaping all data to improve plugin’s overall security.

4.6.8 (February 27, 2018)

  • Improvement. Removed Highcharts JavaScript library because its license isn’t GPL-compatible. We now use ChartJS.
  • Bug fix. Added support to CoAuthors Plus, to prevent a notice thrown in the frontend.

4.6.7 (January 31, 2018)

  • Bug fix. Infinite loop under some weird circumstances in a get_post_metadata filter. This has now been fixed.

4.6.6 (January 17, 2018)

  • Improvement. New filter for disabling widget experiments (nelioab_enable_widget_experiments).
  • Bug fix. Tracking multiple click events properly.

4.6.5 (November 16, 2017)

  • New Feature. Export the results of an experiment in CSV.
  • Improvement. Click actions now can be triggered from any page (instead of tested pages only).
  • Improvement. Cache alternative posts to improve overall speed.
  • Improvement. Detect click events properly, even if the clicked element was removed from the DOM.
  • Improvement. Using original publication and modified date, so that alternative content doesn’t seem “newer”.
  • Bug fix. Match text in click events properly.
  • Bug fix. Added safe guard in our tracking script so that, when checking if we’re inside an iframe, it doesn’t throw an Exception.
  • Bug fix. Sometimes, the “start date” in the experiments result page wasn’t correct. This has now been fixed.
  • Bug fix. When testing the home page, alternative versions should also include the class home in their body tag.

4.6.4 (May 11, 2017)

  • Bug Fix. HTML tags in experiment names are now properly escaped.
  • Bug Fix. CSRF in experiment creation/edition forms has now been fixed.

4.6.3 (April 25, 2017)

  • Improvement. Add JavaScript filter for excluding certain pages from being tracked.
  • Bug Fix. Sometimes, widgets couldn’t be saved. This has now been fixed.
  • Bug Fix. Sometimes, the plugin generated a PHP Fatal Error (file visitor.php line 274). This has now been fixed.
  • Bug Fix. Disqus threads use the appropriate URL. In the previous version, they were split into multiple threads.

4.6.2 (March 13, 2017)

  • Bug Fix. Fixed meta duplication.

4.6.1 (February 9, 2017)

  • Bug Fix. Changed jQuery functions .attr('value'[,...]) to .val([...]).

4.6.0 (February 8, 2017)

  • Improvements. Post conversion actions now searches among custom post types too.
  • Test. Tested with WordPress 4.7.

4.5.11 (December 29, 2016)

  • Improvements. The plugin is now compatible with domain mapper.
  • Bug Fix. SSRF vulnerability located in ajax/iesupport.php has been fixed.

4.5.10 (December 4, 2016)

  • Bug Fix. Form submissions are now properly tracked.

4.5.9 (December 1, 2016)

  • Bug Fix. URLs including an empty page fragment (just the symbol #) can now be properly tested.
  • Bug Fix. Some click events stopped heatmap tracking unnecessarily.
  • Bug Fix. SSRF vulnerability located in ajax/iesupport.php has been fixed.

4.5.8 (October 5, 2016)

  • Improved Results. Results are now cached more frequently in your WordPress server, so that they’re available right when you need them.
  • Improvement. Added a safe guard in the Heatmaps processor that makes the plugin resilient to JavaScript errors generated by the theme or other plugins.
  • Bug Fix. There were some issues synchronizing your running experiments with Nelio’s cloud. This has been fixed in this version by adding some extra checks in the synchronization process.

4.5.7 (September 21, 2016)

  • Bug Fix. Invalid argument in a foreach statement (in visitor.php) is now fixed.

4.5.6 (August 16, 2016)

  • Bug Fix. WooCommerce order complete actions weren’t properly tracked, because of invalid experiment IDs were used. This has now been fixed.

4.5.5 (July 22, 2016)

  • Bug Fix. Form submissions were not properly synched. Now they are.

4.5.4 (July 14, 2016)

  • Compat Improvement. Some themes weren’t compatible with Nelio because some filters were triggered before the setup_theme action. This has now been fixed.
  • Bug Fix. Some click events (for instance, when tracking an element whose ID includes a : char) couldn’t be tracked because they generated a JavaScript exception. This is now surrounded in a try-catch block.
  • i18n Fix. Updated internationalization strings, so that the plugin can be translated in

4.5.3 (June 7, 2016)

  • Bug Fix. AJAX error because of invalid formatted value has now been fixed.
  • Bug Fix. WooCommerce product testing broke short description’s format. This has now been fixed too.

4.5.2 (May 20, 2016)

  • Improvement. nabforce now overwrites both the alternative version the user is supposed to see and the user’s participation in the experiment.
  • Bug fix. Renamed AJAX parameter from filename to classfi so that security plugins (such as Wordfence) do not block Nelio’s requests.

4.5.1 (April 29, 2016)

  • Bug fix. Invalid continue statement changed to return.
  • Bug fix. Some query args were not properly encoded, resulting in an invalid query string. This has been fixed.

4.5.0 (April 8, 2016)

  • Security Fix. This new version fixes a couple of security issues we detected. In particular, we improved input sanitization and we limited file access to those within the plugin’s path.
  • Bug Fix. In the Results page of a post/page experiment, there are two options for previewing an alternative: clicking on a button or on a preview image. The former works, the latter doesn’t. This has been fixed.
  • Minor improvements.

The full change log can be found in changelog.txt.