Why Microsoft is adding Anthropic models into Office 365 Copilot despite OpenAI partnership

Microsoft is preparing to introduce Anthropic’s Claude models into its Office 365 suite, expanding beyond its existing reliance on OpenAI’s technology for Copilot features in Word, Excel, Outlook and PowerPoint. According to a report from The Information, the announcement could be made in the coming weeks.

Until now, Microsoft has leaned primarily on OpenAI’s models to power productivity features. The addition of Anthropic marks a shift in strategy, reflecting the company’s aim to diversify its AI partnerships. Microsoft will reportedly pay Amazon to access Anthropic’s Claude Sonnet 4 model through AWS, in contrast to its arrangement with OpenAI, where it can use models at no additional cost due to its multibillion-dollar investment.

Microsoft maintains that the move is not a sign of friction with OpenAI, despite reports of tension over the AI firm’s proposed restructuring into a public benefit corporation and its push for greater independence. In a statement to The Information, a Microsoft spokesperson said, “OpenAI will continue to be our partner on frontier models and we remain committed to our long-term partnership.”

Executives at Microsoft are said to believe Claude Sonnet 4 performs better in certain areas than OpenAI’s GPT-5, particularly when generating polished outputs such as more visually appealing PowerPoint presentations. Notably, Claude Sonnet 4 is not even Anthropic’s flagship model, suggesting Microsoft sees significant value in its broader performance.

This development also fits within Microsoft’s wider strategy of AI diversification and self-reliance. The company already offers other models, including xAI’s Grok and Anthropic’s Claude, through GitHub Copilot, and has begun developing its own models such as MAI-Voice-1 and MAI-1-preview.

OpenAI, meanwhile, is pursuing initiatives that reduce its dependence on Microsoft. The company has launched a jobs platform positioned as a potential rival to LinkedIn and also reportedly plans to start mass production of custom AI chips with Broadcom by 2026, enabling it to run training and inference on its own hardware.

Despite these parallel moves, Microsoft has confirmed that Copilot pricing will remain unchanged at $30 per user per month, even with Anthropic’s models being added into the mix.