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Optimizely Knowledge Base

Make the transition to Optimizely X Web

  • Optimizely X Web Experimentation
  • Optimizely X Web Personalization
  • Optimizely X Web Recommendations
  • Optimizely Classic

  • Transition your account from Optimizely Classic to Optimizely X
  • Understand which features are migrated automatically and which aren't

Transitioning from Optimizely Classic to Optimizely X Web Experimentation is easy. Administrative users can enable the Optimizely X snippet without making any code changes. The following guide walks you through the transition process.

Learn about the differences between Optimizely X and Optimizely Classic. Or, check out this article to get started.

Want to move an Optimizely Classic experiment into Optimizely X? Read more about that in this article.

Type of transition

You can transition your account in a phased rollout approach or a hard switchover. Read on for more information about each approach.

Phased Rollout

A phased rollout allows you to migrate slowly to Optimizely X. Use this approach to finish running Optimizely Classic experiments and ease onto the new tech stack.

With this approach, you use the bundled snippet to run Optimizely X and Optimizely Classic at the same time.

The bundled snippet is ~50kB larger to incorporate both configurations, which may affect speed.

Build new tests with Optimizely X and pause Optimizely Classic experiments once they run to completion. Once all experiments in Optimizely Classic are complete, you can switch to the standalone snippet for faster performance.

Hard switchover

If you'd like to avoid running the larger bundled snippet on your production site, consider using a separate project or staging environment to evaluate Optimizely X. Test any templates you'd like to migrate to Optimizely X in your environment. 

Once you're comfortable with Optimizely X, pause experiments in Optimizely Classic and enable the Optimizely X snippet.

Enabling the snippet

The new snippet includes project-level settings for Optimizely X, Optimizely Classic, or both. Use both when you're trying out Optimizely X but running experiments on Optimizely Classic at the same time. Once you're ready, enable your Optimizely X snippet in Settings to reduce snippet size and improve performance.

You will need to have Administrator privileges to enable Optimizely X in the snippet settings.

Transitioning features

Some features transition from Optimizely Classic to Optimizely X automatically and some need to be manually transitioned.


In Optimizely X, you'll define URL targeting on pages. Pages are reusable "templates" that can be used across different campaigns and aren’t tied to any single experiment until you add it to the campaign. When manually setting up a page in Optimizely X, select an activation mode for each page from the options shown below:

To set up two experiments with the same URL targeting (for example, across all product detail pages) but different activation modes, you'll need to create two separate pages.


In Optimizely X, goals are called events. They're now more powerful and can be used across different campaigns.

Optimizely Classic goals don't show up in Optimizely X.

For custom events coded for your site, the POST request is still sent. You don't need to make any code changes. Simply add the custom event in Optimizely X:

  1. Select the Implementation dashboard, then click Create New Event.

  2. Then select Custom event

The Optimizely Customer Success team can help you migrate your custom events. If you'd like all your events migrated programmatically, please submit a support ticket.


Audiences are shared between Optimizely Classic and Optimizely X. All audiences created in Optimizely Classic will show up in Optimizely X and vice versa.

However, Optimizely Classic audiences that include custom tags don't currently work in Optimizely X. This audience type has been deprecated because in Optimizely X you can instead use pages to replace this functionality.

Also, Optimizely X audiences that include visitor behaviors (a feature available only through Optimizely X Web Personalization) don't currently work in Optimizely Classic.


Optimizely X uses a new version (v2) of the REST API. If you use the v1 REST API, use our developer documentation to update to v2.

There's also a new version of the JavaScript API. Most JS API methods from Optimizely Classic are backwards-compatible. See our developer documentation for more details.


Our most popular analytics integrations work in both Optimizely Classic and Optimizely X. Audience and data management platform (DMP) integrations also work in both.

We're actively building more integrations. Check our list of current integrations.

Experiments and results

Experiments in Optimizely Classic and Optimizely X live on their own platforms. Optimizely X experiments don't show up in Optimizely Classic, or vice versa; this means experiments won't be automatically migrated. However, you'll always be able to see your Optimizely Classic experiments and results -- even if you've enabled the Optimizely X standalone snippet.

Here's how to quickly build your Optimizely Classic experiment in Optimizely X.