2026 Optimizely Feature Experimentation release notes

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May 18

  • (Beta) Released Feature Rollouts, which is a rule type that combines the simplicity of targeted deliveries with the measurement power of A/B tests. Feature Rollouts let you progressively release a single variation to defined audiences, control traffic allocation, and track impressions, conversions, and business metrics during the release. Use Feature Rollouts when you want progressive exposure with metric tracking, not a binary on or off delivery. See Run Feature Rollouts in Feature Experimentation.
  • Released v4.0.0 of the React SDK. This rewrite modernizes the hook API. It also adds async decision support for Contextual Multi-Armed Bandit (CMAB) experiments and asynchronous user profile services. This update includes various changes, including the following:
    • Redesigned the hook API with useDecide, useDecideForKeys, and useDecideAll. These hooks return a { decision, isLoading, error } object instead of a tuple. See Decide hooks for the React SDK v4+.
    • Added async decision hooks (useDecideAsync, useDecideForKeysAsync, useDecideAllAsync) to support CMAB experiments and asynchronous user profile service lookups.
    • Introduced the useOptimizelyClient and useOptimizelyUserContext hooks. They replace the withOptimizely higher-order component and the legacy useDecision, useExperiment, useFeature, and useTrackEvent hooks.
    • Upgraded the underlying JavaScript SDK to v6 and raised the minimum Node.js version to 18.0.0. See Initialize the React SDK.
    • Dropped CommonJS support, so the package now ships as ECMAScript modules (ESM) only. Renamed the OptimizelyProvider optimizely prop to client. See Upgrade the React SDK from v3 to v4 for the full list of breaking changes.
    • See the full release notes on GitHub.

May 5

Added Owner and Teams fields to flags. The Owner field defaults to the flag creator. You can edit it from the flag Settings page. The Teams field supports multiple teams per flag and displays as a column on the Flags list. See Manage flags for information.

April 29

Released the Optimizely Experimentation MCP server, which connects AI clients to your Experimentation data using the Model Context Protocol (MCP) open standard. Supported clients include Claude Desktop, Claude Code, Claude.ai, Cursor, Visual Studio Code with GitHub Copilot, and Windsurf. Authenticate with OAuth 2.0 through Opti ID and interact with your experimentation data through natural language.

April 28

  • Released Contextual multi-armed bandits (CMABs). CMABs use Optimizely Opal to dynamically reallocate traffic to the best-performing variation for each user segment based on contextual attributes. CMABs continuously balance exploration and exploitation as response data accumulates, so personalized experiences reach users faster than with traditional A/B testing.
  • Added the ability to copy a rule to another environment within the same flag. Copied rules arrive in Draft status in the destination environment, so you can review and edit them before saving. Use this to replicate experiment configurations across environments without manual recreation. See Manage rules for information.
  • Released Custom Fields, which let you attach structured metadata to flags. Choose from five field types: Label, Text, Numerical, Link, or Boolean, and mark each field as required or optional. Display custom fields as columns on the Flags Dashboard to filter, sort, and group flags, which improves discoverability and keeps metadata consistent across teams.
  • Released Flag Statuses, which automatically assign one of six lifecycle statuses to each flag: Draft, Testing, Live, Paused, Stale, or Archived. Statuses are calculated from a flag’s ruleset state, environment, and recent activity. Use flag statuses to surface flags that need attention and prevent unused flags from accumulating in your project.

March 30

March 13

  • Released Global Holdouts, which lets you designate a small percentage of users as a control group, ensuring they do not experience any experiments or new feature rollouts. This lets you directly compare outcomes between users who experience variations identified as winners during A/B tests and those who only see the default "off" variation for feature flags in your project.

January 22

  • Added the Experimentation Program Overview agent to the Opal Agent Directory which creates a report on how your Optimizely Experimentation program is performing using top experiment and win rate data. 
  • Released the following system tools in Optimizely Opal to help you with your Feature Experimentation projects. See System tools for Feature Experimentation for the full list of available Opal tools, including when to use them, variables, and example prompts. 
    • exp_get_schemas – Retrieves detailed schemas for various Optimizely entities relevant to Feature Experimentation.
    • exp_execute_query – Executes a template-based query to fetch specific data from your Optimizely Feature Experimentation instance. It lets you retrieve detailed information about various entities such as feature flags, rules, environments, attributes, and events, based on your specified criteria.
    • exp_program_reporting_top_experiments – Retrieves experiments that have generated the highest positive or negative lift values within a specified timeframe. It focuses on the performance of individual tests, letting you see which variations of your features are performing best (or worst) against your chosen metrics.
    • exp_program_reporting_underperforming_experiments – Helps you identify A/B tests that are not yielding significant or positive results, letting you quickly decide whether to stop, re-evaluate, or iterate on them.
    • exp_program_reporting_win_rate – Gives you a high-level overview of the success of your experimentation program by calculating the win rate over a specified period. It is a key metric for understanding the efficiency and impact of your product development cycle.