The best part? It's all open source, warehouse-native, and transparent - you can audit exactly how we calculate everything.

Want to see the implementation details? Check out our deep dive: blog.growthbook.io/holdouts-dee...

We built this because our community of 5,000+ engineers kept asking for better ways to prove impact. One customer told us: "Holdouts helped us discover our 'successful' feature was actually causing a 2% revenue decline after 30 days."

🪝 Catch delayed effects - Some changes take weeks to show impact
⚖️ Measure cumulative impact - Stack multiple features and still understand individual contribution
🤝 Build trust in your data - Show stakeholders exactly what drove that revenue increase

Think of them as your experiment's control group that persists even after launch. While 95% of users get your shiny new feature, 5% stay in the original experience. This gives you a clean baseline to measure against.

The kicker? ChatGPT already drives 10% of new signups for companies like Vercel. This isn't future speculation - it's happening now.

Here's our full guide: blog.growthbook.io/guide-to-geo/

Question: Is anyone A/B testing GEO yet? How is it working?

• There's no page 2 in AI search - you're either in the answer or you're invisible
• Statistics boost AI visibility by 33.9% - AI can't create data, so it gravitates toward sources that provide it
• Most AI traffic is invisible - it shows up as "Direct" in analytics

We provide an in-depth guide and a video tutorial to help you set it up efficiently. Watch the tutorial here: www.youtube.com/watch?v=tg85...

If you're building on Vercel and NOT running experiments... what are you even doing? 😅

🔗 Install from Vercel Marketplace: vercel.com/marketplace/...
#Vercel #NextJS #WebPerformance #EdgeComputing

The technical details you care about:

→ SDK size: <15KB gzipped
→ Evaluation time: <1ms at edge
→ Zero cold starts
→ Works with App Router, Pages Router, and Edge Runtime

Plus, your feature flags now live where your code deploys. No more environment mismatches.