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Microsoft is encouraging its engineers to branch out from its own Copilot coding assistants.
While Microsoft continues to champion its GitHub Copilot coding assistant, its engineers have been quietly experimenting with Anthropic’s Claude Code – testing how it performs at real-world coding and prototyping tasks.
According to The Verge, Microsoft’s CoreAI team – which focuses on AI-powered developer tools – has been testing Anthropic’s Claude Code for several months. Engineers in the Experiences and Devices division – responsible for Windows, Microsoft 365, Outlook, Teams, Bing, Edge, and Surface – have now also been asked to install and test it. The report also notes that developers have been experimenting with other coding assistants, such as Cursor.
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Developers are increasingly comfortable assessing and experimenting with a variety of models and AI coding tools as they discover which work best for certain tasks.
Microsoft has also approved – and encouraged – non-technical staff, such as designers and project managers, to experiment with Claude Code for rapid prototyping.
“Companies regularly test and trial competing products to gain a better understanding of the market landscape,” a Microsoft spokesperson told LeadDev.
New partner?
The willingness to experiment with Anthropic models internally is notable because Microsoft’s flagship GitHub Copilot coding assistant has long defaulted to models from Anthropic’s arch rival OpenAI.
Microsoft established a strategic partnership with OpenAI as long ago as July 2019, by committing $1 billion to support OpenAI’s research and development and provide the company with access to its Azure cloud computing infrastructure.
In January 2023, after the launch of ChatGPT, the two companies expanded that partnership with a new multiyear, multibillion‑dollar investment – widely reported to be around $10 billion.
However, in September 2025, it was announced that Microsoft would enter a new partnership with Anthropic to bring its Claude AI models into Office 365, marking a shift away from relying solely on ChatGPT.
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For users, this means that AI features in apps like Word, Excel, and PowerPoint are now powered by a combination of different AI models depending on the task.
A spokesperson from Microsoft told LeadDev that OpenAI continues to be its “primary partner and model provider on frontier models.”
“We remain committed to our long-term partnership,” they added.

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