Automatic code reviews with OpenAI Codex

The video showcases OpenAI’s Codex as an advanced AI coding teammate that automates code reviews by analyzing entire codebases, running tests, and providing precise, context-aware feedback to catch bugs and improve code quality. Integrated seamlessly into developer workflows, Codex enhances productivity by enabling collaborative interactions, customizable review guidelines, and both cloud-based and local code review capabilities.

The video introduces OpenAI’s Codex as an effective coding teammate that integrates seamlessly with developers’ tools and team workflows, with a particular focus on automating code reviews. Roma and Maya explain that code review is a critical workflow for engineering teams, and Codex has been specifically trained to identify bugs and investigate issues within codebases. This capability is designed to help alleviate the bottleneck caused by human verification as AI-generated code production increases.

Maya, who works on the alignment team at OpenAI, highlights the importance of scaling verification abilities alongside AI capabilities. The code review models are trained not only as a research exercise but also to interact with OpenAI’s own codebase and to be available externally. This approach aligns with OpenAI’s philosophy of iterative deployment and grounding technology in real-world use. Enabling Codex for code review is straightforward, and once activated, it automatically reviews pull requests (PRs) submitted to the repository.

The video demonstrates how Codex reviews PRs by analyzing the entire codebase, not just the diffs, allowing it to understand dependencies and the broader context. Codex can also run tests and execute commands to verify its findings, making it more than just a static analysis tool. The model is trained to prioritize catching meaningful bugs with high precision, reducing false positives and ensuring that its comments are helpful rather than annoying. This practical evaluation through real-world use is key to its effectiveness.

Internally at OpenAI, Codex has already proven valuable by catching critical bugs that could have delayed important model releases or caused configuration issues. It also helps developers confidently contribute to unfamiliar codebases by providing insightful feedback. The video showcases a collaborative workflow where developers can interact with Codex, ask it to review specific areas, and even request it to fix identified issues, enhancing productivity and code quality.

Finally, the video touches on the flexibility of Codex, including its integration with agents.mmd, an open format for coding agents that allows custom instructions and guidelines to tailor code reviews to specific team needs. Codex also supports local code reviews through a command-line interface (CLI), enabling developers to catch bugs before submitting PRs. Overall, Codex serves as a powerful coding partner both locally and in the cloud, helping teams ship safer, higher-quality software more efficiently.