2023 Optimizely Feature Experimentation release notes

  • Updated

The following is a cumulative list of enhancements and major bug fixes in each Optimizely Feature Experimentation release.

Because Optimizely Feature Experimentation releases new features and fixes as soon as they are ready, this list will update regularly. Follow this article to receive notifications as soon as new content is added.


New feature

  • Released automatic SRM detection.
    • Every customer needs to quickly identify problems and protect their experiments from unintended traffic imbalances. Optimizely now automatically runs SRM detection tests embedded within your Stats Engine A/B experiments. When the Optimizely detector finds unusual imbalances in visitor traffic to an experiment's variations, it identifies the severity and then sends out an in-product notification. You can now detect experiment problems early and without manual effort. See Optimizely's experiment health status documentation section.


  • Released webhooks for all environments, not just the primary environment.
    • Also released an update where only the updated environment's datafile is revised. For example, if you update the development environment, Optimizely will only create new datafile revisions for that development environment.
  • Released the ability to schedule changes to your rule's audience



Released platform enhancement enabling you to deliver feature flag and experiment changes to your end-users significantly faster (~90% average performance improvement, based on initial Production data). 

New features


Experiment Collaboration was released

Experiment Collaboration is designed to help teams manage their experiment ideation, planning, and hypothesis-creation process more effectively. Learn more and create your first hypothesis by following the Get started with Experiment Collaboration guide.

Feature Experimentation API improvements


Breaking change SDK releases

The Advanced Audience Targeting integration with Optimizely Data Platform (ODP) for the following Feature Experimentation SDKs is now in beta:

New API added to the SDK's OptimizelyUserContext

  • fetchQualifiedSegments() this API will retrieve user segments from the ODP server. The fetched segments will be used for audience evaluation. The fetched data will be stored in the local cache to avoid repeated network delays.
  • When an OptimizelyUserContext is created, the SDK will automatically send an identify request to the ODP server to facilitate observing user activities.

New APIs added to the SDK's OptimizelyClient

  • sendODPEvent() – customers can build and send arbitrary ODP events that will bind user identifiers and data to user profiles in ODP.
  • createUserContext() – (For server-side SDKs only) – with anonymous user IDs, user-contexts can be created without a userId. The SDK will create and use a persistent VUID specific to a device when userId is not provided.

Additional releases

Bug Fixes

  • Fixed an error where Cross-project events do not always appear in all projects metrics.
  • Fixed various bugs with change history:
    • Fixed a bug that made change history unavailable for certain customers.
    • Fixed a bug where change history would return a 403 error.
    • Fixed a bug where change history would display Something Went Wrong and not load the change history.
    • Fixed a bug where existing rules would show as created instead of updated.
    • Fixed a bug where change history did not log the updated rule when the rule was added, updated, or removed from an exclusion group.
    • Fixed a bug where deleting a variation or rule also deleted the history of the variation or rule.
  • Fixed a bug on the Reports page where updated rule descriptions would not display.
  • Fixed a bug where new targeted delivery rules could not be saved.
  • Fixed a bug where pages would sometimes not populate when switching between differing project types.

Feature Experimentation API improvements

Additional enhancements



  • Improved the layout of the Flags list for better usability.
  • Rules are set as paused on creation, which enables staging rules at scale.

Bug Fixes

  • Fixed an issue where the Flags UI dashboard was not loading for some customers.
  • Fixed an issue where a 500 error was being reported when trying to change the reporting date range in Program Management.