Microsoft Shifts Internal Teams to GitHub Copilot CLI, Phasing Out Claude Code

Microsoft is making a significant internal strategic shift, reportedly phasing out the use of Anthropic's Claude Code among its Experiences + Devices division, which encompasses major products like Windows, Microsoft 365, Outlook, Teams, and Surface. Engineering teams within this division are being instructed to migrate to GitHub Copilot CLI, with a firm deadline of June 30, 2026, coinciding with the end of Microsoft's fiscal year. This decision is attributed to several factors, including cost-cutting initiatives as the large-scale adoption of generative AI tools drives up expenses across the tech industry. Furthermore, Microsoft aims for toolchain unification and greater control over its internal development environment. While Claude Code had become popular among Microsoft engineers for rapid prototyping and coding assistance, the company now seeks to standardize on GitHub Copilot CLI, a product it can directly shape around its specific repositories, workflows, security requirements, and engineering standards. Despite this internal shift, Microsoft's broader relationship with Anthropic is not entirely severed. Claude models, including Sonnet, Opus, and Haiku, will remain accessible within GitHub Copilot CLI alongside OpenAI and Microsoft's in-house AI models. This move is seen as a way for Microsoft to intensely "dogfood" its own AI coding tool, leveraging its world-class engineers to rapidly improve Copilot CLI and solidify its position as the primary command-line AI coding solution.