At Meta, WebRTC powers real-time audio and video across various platforms. But forking a large open-source project like WebRTC within our monorepo presents unique challenges – over time, an internal fork can drift behind upstream, cutting itself off from community upgrades.

We’re sharing how we escaped this “forking trap” – from building a dual-stack architecture that enabled safe A/B testing across 50+ use cases, to the workflows that now keep us continuously upgraded with upstream.

This approach improved performance, binary size, and security – and we continue to use it today to A/B test each new upstream release before rolling it out.

At Meta, real-time communication (RTC) powers various services, from global Messenger and Instagram video chats to low-latency Cloud Gaming and immersive VR casting on Meta Quest. To meet the performance demands of billions of users, we spent years developing a specialized, high-performance variant of the open-source WebRTC library.

Permanently forking a big open-source project can result in a common industry trap. It starts with good intentions: You need a specific internal optimization or a quick bug fix. But over time, as the upstream project evolves and your internal features accumulate, the resources needed to merge in external commits can become prohibitive.