Microsoft uses internal AI Copilot for code review, impacts 600,000 PRs per month

GitHub Copilot is an impressive tool that uses the power of Generative AI (GAI) to write both boilerplate and complex code on behalf of programmers. Microsoft recently open-sourced its implementation of the programming assistant in Visual Studio Code for developers to take advantage of. Details have also been revealed about the extent to which the AI assistant is being used in Microsoft's own internal development process.

The Redmond-based tech giant said it is using an internal AI programming assistant to review code. GitHub Copilot now impacts more than 600,000 pull requests (PRs) per month — nearly 90% of the company's total PRs. The code review assistant doesn't have a specific name, but was developed with the support of the AI & Data team within Microsoft's Developer Division. The lessons learned from this internal implementation are then applied to GitHub Copilot's code review feature for external customers.

Microsoft also pointed out the problems with large-scale code review, including:

1. Reviewers sometimes focus too much on syntax and miss more important issues.
2. Code authors often find it difficult to determine the context in complex PRs.
   This causes PR delays - and this is where AI code review comes in handy, solving most problems in a short time.

In return, the code review assistant will be able to assist with the following aspects:

1. Automatic code testing
2. Give feedback
3. Problem Alert
4. Suggest improvements and optimizations
5. Generate PR summaries
   Reviewers can also engage in Q&A with the assistant to gain deeper understanding of the code. Teams can also configure the assistant and customize it for specific issues via prompts.

Microsoft boasts about the positive impact of this solution: faster review cycles, improved code quality, and learning opportunities for both developers and reviewers. The company believes this is the future of programming, which is why they are sharing their internal experience and tools with customers through GitHub Copilot code review, which officially launched in April 2025.

Isabella Humphrey

Update 17 July 2025