Software Release Glossary
Most commonly used terms and acronyms by product managers, engineers and devops, regarding deployment strategies

Server-Side Testing

For a long time, marketing teams have been relying on client-side testing to run experiments on a website’s front-end features. However, there is no denying that web applications have increased in complexity which have necessitated more sophisticated approaches to testing, mainly focused on the back-end.

This is where server-side testing becomes indispensable as it widens the possibilities of experimentation.

What is server-side testing?

Server-side testing refers to any type of testing, usually A/B testing, that occurs directly on the web server instead of the user’s browser.

In contrast, client-side testing is where experimentation occurs on the client side through Javascript that runs in the browser to optimize the customer experience.

Therefore, in server-side testing, all the work happens at the server level instead of the browser.

Client-side solutions usually don’t require any technical expertise since they generate the experiment code themselves. Therefore, they are particularly popular with marketing teams for conversion rate optimization purposes. 

Meanwhile, server-side solutions need technical and coding skills as you will need to incorporate experiments into your code and deploy them. 

This doesn’t mean that marketing and product teams cannot make use of such solutions. Non-technical teams would define the experiments in server-side tests and then the engineers can execute them, promoting collaboration and a truly agile workflow. The experiments can then be monitored and analyzed through a dashboard.

Benefits of server-side testing

Since experiments are not rendered on the browser, the experiment is not as noticeable on the user side. Thus, the page load time will suffer minimal impact thereby bypassing the so-called ‘flicker effect’, which is when the original page loads and then is replaced by the test variation. This flicker is usually seen by the user.

Furthermore, with server-side testing, your tech team has full control over the server-side code so they can build experiments without any constraints.

One of the most important benefits of such testing is while client-side testing can only help you test the look and feel of your website, server-side testing allows you to test anything on the back-end such as algorithms and back-end logic. Basically, you can test anything back-end in your application.

Finally, server-side testing is not just limited to testing websites but it also enables you to carry out omnichannel experiments such as on mobile apps and email. Thus, there’s no limit to the devices and platforms you can test.

Server- vs client-side testing

Client-side testing can be quite beneficial to teams because it’s so easy to set-up, particularly by non-technical teams. It also helps you gain valuable insights in order to customize and optimize the user experience while investing little time and money.


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Up to a certain point, client-side testing may be sufficient, especially for testing small changes on your website like the visual aspects to your website. After some time, however, and as your application becomes more advanced, you may want to do more in-depth testing techniques.

Server-side testing is useful for running more sophisticated experiments since the implementation is more direct allowing you to test across the full stack. With this type of testing, you can delve deeper into experiments that explore how a product works.

Whatever method of testing you decide to use will ultimately depend on your objectives and use cases. You can even use both together to heighten productivity and achieve maximum impact.

For example, AB Tasty is our client-side solution that helps marketers optimize conversions while Flagship is our server-side tool that you can use to enhance functionality of your products and/or services.

Using feature flags to conduct server-side testing

Feature flags are a software development tool that allows you to to decouple deployment from feature release making releases quicker and less risky.

Therefore, with feature flags you can conduct server-side A/B tests by rolling out new features to a small group of users. You can then measure their performance on this group of users before rolling out to everyone else.

If you want to try your hand in server-side testing, Flagship by AB Tasty offers server-side experimentation in order to conduct safe experiments for your features by setting up user-targeting and KPIs to track and puts you on the road to quicker and safer releases.


Server-side testing has become a necessity for increasingly complex modern applications. In contrast to client-side testing, it allows for full-scale testing on various channels.

With Flagship by AB Tasty, you can carry out secure and robust experiments to empower teams and improve the quality of your products.

For more of an in-depth look at both types of testing and their pros and cons, check out our blog article on how to drive digital transformation with client- and server-side experience optimization.

More terms from the glossary
Smoke Testing

Smoke testing is a rapid regression test of major functionality to detect early errors and indicate whether the product is ready for further testing.

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Version Control

Version control, or source control, is the practice of managing and tracking changes to software code.

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Software Development Life Cycle

Software development life cycle (SDLC) refers to the different stages that a software goes through from planning to completion.

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