Server-side Testing

Expand your possibilities with Server-side testing.

What is Server-side Testing? On a basic level, when delivering A/B or multivariate tests using Server-side tools, no changes are made at browser level; everything happens on the server. When a user requests a page or service, your servers and ours would decide what variation to show and return it to the user directly.

By direct comparison, the most common form of A/B testing, known as Client-side testing, uses a JavaScript tag to load changes to an existing page on your website ‘on the fly’ within the user’s browser.

How does it work?

At Webtrends Optimize, all tests and projects are uniformly built, so in the case of Server-side testing, we use the exact same UI in our Advanced Editor as we would for any Client-side A/B tests or projects. And, because you have access to all the same tools and features as we do, you can easily build tests whichever type you choose – at no additional cost.

Details on how to utilise Server-side testing as a Webtrends Optimize customer is fully documented within our comprehensive Help site. Explaining in detail how to call tests using our API. And of course, we’re on hand to support or guide you through the process too.

Young woman prov idign support for Server-side testing to a young man
Man typing on keyboard highlighting the benefits of Server-side testing

Benefits of Server-side Testing

Speed: We’re making a single, very lightweight call as we’re only retuning just an identifier instead of multiple code changes, so the entire process should be faster; under 250ms in most cases.

Reach: Everything resides on your server, so there’s nothing you can’t test with this method (for web pages). Whether purely visual or a core function such as pricing, Server-side testing can handle it all.

Effort: Pages are usually easier to build than to modify. If you’re toggling features on/off, or between two pages, tests are usually much quicker to build.

Longevity: Again, if we’re just toggling things on/off, optimals are just as easy as leaving it always “on”. This makes it the preferred route for all development, so you’re not doubling up on effort where optimals are found.

What can you do with Server-side Testing?

Of course, while it’s great to understand the core differences between Client and Server-side testing, how it technically works, and what the benefits are, the key question is what can you actually do with it? Well, quite a lot actually!

If you have a new booking journey or funnel, or even a whole new website, you can (and should) test one against the other to ensure you leave nothing to chance and get the uplift you’re looking for when you put it live. But it's not just useful for full site re-designs - a few more of the many examples of how you might use Server-side testing are highlighted below.


Test offering a discount to a ‘specific’ type of user directly on the products across your site (or adding a voucher code). You can also test how much the discount should be, to drive the optimal increase in sales.

Sort Order

We know that the sort order on product listing pages can have a big influence on what, and if, the user selects a specific product. Use Server-side testing to test different algorithms against one another.

Support Releases

Use Server-side testing to support your own release management. Not only to prove the value of the changes – but also to control deployment and manage risk by limiting exposure & avoid big bang deployments.

So, I should just use Server-side testing then?

Not necessarily. Although Server-side testing has some huge benefits, especially for changes that aren’t solely in the UI, Client-side testing also has some significant assets in its locker.

You don’t always require any technical development resource with Client-side for one, meaning as a marketer you can just jump into our WYSIWYG editor and get started without any IT assistance. And for straightforward tests and tweaks to already fairly well performing pages (which can still deliver great advantages) A/B testing via Client-side could be your best option.

As with all website optimisation it’s about analysing what you want to achieve and picking the right tool for the job. As a Webtrends Optimize customer both methods are available to you, as are all of our Web Optimisation and Personalisation tools, at one fixed price. So you’ll always have the right tool – and even someone on hand to show you how to use it if needed.

Choose your solution

We have a range of website optimisation solutions available to best suit the needs of your business.

Get in touch

Want to know more about Server-side testing, or how Webtrends Optimize can help your increase your conversions? Click below to send us a message or call us on 0333 444 5502.

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