“Back in 2024, we were seeing that engineers would get their first review within 3 hours. Now in 2026, that has grown to 9 hours uh in addition to all of the volume changes. So, in short, code review is now the bottleneck that we are running into.”

Uber has thousands of engineers across hundreds of teams working in six language-specific monorepos. As PR volume and size grew, the time to a first review tripled, which is why Uber built uReview, its in-house multi-agent code reviewer. Quoted from YouTube’s auto-generated captions.