This release continues the momentum of GrowthBook 4.0 by adding two of our most requested Enterprise features - Holdouts and Experiment Dashboards. Plus, we’ve made several significant enhancements to our integrations with AI coding tools and our MCP server capabilities. If you’re not yet using GrowthBook with your AI coding tools, we highly recommend it!

Read on to learn more about these features and everything else we’ve been working on these past 2 months.

Holdouts

MCP Server

Holdout experiments measure the long-term impact of features by maintaining a control group that doesn't receive new functionality. While most users experience your latest features and improvements, a small percentage remain on the original version, providing a baseline for measuring cumulative effects over time. Read more about holdouts. 

Experiment dashboards

Experiment Dashboards let you create tailored views of an experiment. Highlight key insights, add context, and share a clear story with your team. For example, highlight the key goal metric results, show an interesting breakdown by dimension, and link to supporting external documents, all in a single view. Dashboards are available for all Enterprise customers. We have a lot planned for this, so stay tuned!

AI features

This release integrates AI to accelerate your workflows in GrowthBook. Auto-summarize experiment results, get help writing SQL, improve hypotheses, detect similar past experiments, and more. These features are available even if you’re self-hosted, just supply an OpenAI API key. See the AI features in action or read detailed information on how these features work.

MCP updates

We've updated our MCP Server to allow you to create experiments directly from your AI coding tool of choice, without needing to context switch to GrowthBook. This change unlocks a bunch of new, exciting workflows, and we can't wait to see how you use it!

Vercel native integration

We're excited to announce that GrowthBook is now available as a native integration in the Experimentation category on the Vercel Marketplace! This integration makes it easier than ever to add feature flagging and A/B testing to your Vercel projects, with streamlined setup, unified billing, and ultra-low latency performance. Read more on our announcement post.

Pre-computed dimensions

You can now pick a set of key experiment dimensions and pre-compute them along with the main experiment results. This allows for more efficient database queries and instant dimension breakdowns in the UI. Read more in our docs.

FerretDB support

FerretDB is a MongoDB-compatible, open-source database that is free to use. It serves as a drop-in replacement for MongoDB, converting MongoDB wire protocol queries to SQL and using PostgreSQL as its backend storage engine. We're pleased to support FerretDB officially!

Sanity CMS integration

Sanity is a real-time content backend for all your text and assets. You can now use GrowthBook feature flags to seamlessly test different content variations within Sanity. Check out our announcement video and tutorial or our docs. 

The 4.1 release includes over 150 commits, way more than we can quickly summarize here. View the release details on GitHub for a more comprehensive list.  As always, we love feedback - good and bad. Let us know what you think of the new features and what you want to see as part of 4.2!