Over the past year, the size and demands on our monorepo have increased at a staggering pace. It was clear that we needed to revamp our source control system to scale to the level of concurrent work that Codex makes possible.

We built Pando, a new backend for Git repositories, without interrupting any engineering work or changing how our team uses Git. Pando now powers all development in OpenAI’s monorepo. Pando is designed to meet two ambitious goals: first, horizontally scalable writes, optimized for concurrent pushes to many branches. And second, maximize read throughput, so clients can download data fast enough to fully saturate their available network bandwidth.

We met these goals while retaining compatibility with the Git protocol and client, enabling both our engineers and agents to seamlessly adopt Pando into their existing workflows. In production, Pando cut median push latency by nearly 5x. It now delivers nearly a petabyte of Git data per day.

Here, we’ll cover our motivations for building a new source-control system, along with why we chose to retain compatibility with Git. We’ll compare our system with common approaches to scaling Git, describing why Pando is uniquely capable of meeting OpenAI’s scalability needs. We also discuss what’s next, and how we’ll continue contributing to Git to support agent-scale work.