---
title: Javascript-SDK - 6.0.0
slug: feature-experimentation/release-notes/javascript-sdk-6-0-0
docTags: 
createdAt: 2026-07-20T15:45:10.133Z
---

## \[6.0.0] - May 29, 2025

[#600---may-29-2025](docId\:aL-7EIjyoGronO_fwnI3a)

### Breaking Changes

[#breaking-changes](docId\:aL-7EIjyoGronO_fwnI3a)

- Modularized SDK architecture: The monolithic `createInstance` call has been split into multiple factory functions for greater flexibility and control.
- Core functionalities (project configuration, event processing, ODP, VUID, logging, and error handling) are now configured through dedicated components created via factory functions, giving you greater flexibility and control in enabling/disabling certain components and allowing optimizing the bundle size for frontend projects.
- `onReady` Promise behavior changed: It now resolves only when the SDK is ready and rejects on initialization errors.
- Event processing is disabled by default and must be explicitly enabled by passing an `eventProcessor` to the client.
- Event dispatcher interface updated to use Promises instead of callbacks.
- Logging is disabled by default and must be explicitly enabled using a logger created via a factory function.
- VUID tracking is disabled by default and must be explicitly enabled by passing a `vuidManager` to the client instance.
- ODP functionality is no longer enabled by default. You must explicitly pass an `odpManager` to enable it.
- Dropped support for older browser versions and Node.js versions earlier than 18.0.0.

### New Features

[#new-features](docId\:aL-7EIjyoGronO_fwnI3a)

- Added support for async user profile service and async decide methods (see documentation for [User Profile Service](docId\:SBsPoqyJBy1uGzOZK8Evz) and [Decide methods](docId\:SlmvozhQJ1rmI6AIIoqql))

### Migration Guide

[#migration-guide](docId\:aL-7EIjyoGronO_fwnI3a)

For detailed migration instructions, refer to the [Migration Guide](docId:6vdzL6aTnB15l3Jb11osg).

### Documentation

[#documentation](docId\:aL-7EIjyoGronO_fwnI3a)

For more details, see the official documentation: [JavaScript SDK](docId:8PWUc59E_yQaRlOmUc5JA).

[https://github.com/optimizely/javascript-sdk/releases/tag/v6.0.0](https://github.com/optimizely/javascript-sdk/releases/tag/v6.0.0)