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Optimizely Knowledge Base

What to expect when you migrate from Optimizely Web to Full Stack

  • Identify the differences between Optimizely Web and Full Stack
  • Choose the correct Optimizely product for your project 


Transitioning from Optimizely Web to Full Stack is a milestone for your company’s experimentation program. Now that you’ve fully embraced a culture of experimentation, here’s a short run-down of some of the major differences between the two products.

Growth-focused vs product-focused

Optimizely Web is a client-side experimentation tool for marketing or growth teams. It’s accessible even for those who lack strong technical skills. X Web experiments often focus on goals like optimizing conversion rates in marketing or purchasing funnels.

Full Stack, on the other hand, is a server-side experimentation tool. It’s aimed at product development teams who want to experiment with their product and its features without incurring any performance degradation. Full Stack users are less concerned with conversion rate optimization and instead work to optimize products for metrics like engagement, retention, usage, and lifetime value.

Technical skill

As we mentioned, X Web doesn’t require users to have a high level of technical sophistication. In fact, it provides users with a WYSIWYG visual editor for building experiments. That means you can take your idea from hypothesis to completed experiment without ever writing a single line of code.

But it’s not so simple when it comes to Full Stack. Setting up server-side experiments with Full Stack often involves writing new code and deploying it on your organization’s servers, tasks best suited for skilled developers.

Snippet vs SDK

With Optimizely Web, implementation is very straightforward. Just add a single line of code—the snippet—to the code of any page where you’d like to run an experiment.

With Full Stack, there is no snippet. Instead, it relies on SDKs in a variety of popular development languages.

Speed vs depth

If your focus is on optimizing various aspects of your site’s interfaces, you’ll want to use X Web for that. It’s the fastest way to test the look and feel—layouts, messaging, colors—of your site’s user experience, with no code releases required.

By contrast, Full Stack’s server-side approach makes it easy to test underlying features, business transactions, complex algorithms—in other words, how your product actually works. But deploying an experiment in Full Stack isn’t as fast as it is in X Web; you will need to adhere to server code release standard practices, like code review and QA.

Single-channel vs multi-channel

The experiments you build with X Web will generally run in one channel, usually your organization’s website. Full Stack lets you experiment across multiple channels at once—web, mobile, SMS, and email, for example.


Despite its complexity, you may actually get better performance from Full Stack than X Web. That’s because server-side experimentation can be more efficient than experimenting in the browser, which can sometimes affect pageload times or induce a slight flickering effect.

Learn more

To find out more about Full Stack, see our Developer Documentation, or check out our blog posts on the subject.