Microsoft will add Anthropic’s artificial intelligence (AI) to Office 365 after tests showed it creates better PowerPoint slides and handles spreadsheet work more effectively than OpenAI.
The tech giant plans to announce the change within weeks, according to The Information. Anthropic’s Claude Sonnet 4 will work alongside OpenAI’s models in Word, Excel, Outlook, and PowerPoint.
This marks the end of Microsoft’s exclusive use of OpenAI for AI features across its productivity software, which serves more than 430 million paying users worldwide.
Tests revealed Anthropic’s AI makes “more aesthetically pleasing” PowerPoint presentations. It also excels at automating financial functions in Excel. Company sources said Claude Sonnet 4 “performs better in subtle but important ways” than OpenAI’s GPT-5.
Microsoft will pay Amazon Web Services (AWS) to access Anthropic’s models, creating an unusual arrangement where the tech giant relies on a cloud computing rival to power its flagship software. AWS serves as one of Anthropic’s largest investors and primary cloud provider.
Despite paying for Anthropic’s technology, Office users won’t see price increases. Copilot will stay at $30 per user per month. This differs from Microsoft’s OpenAI deal, where the company’s massive investment provides free access.
“OpenAI will continue to be our partner on frontier models and we remain committed to our long-term partnership,” a Microsoft spokesperson said.
The move comes as both companies pull away from their exclusive partnership. OpenAI has added Google Cloud to its computing network, reducing its reliance on Microsoft’s infrastructure as demand for AI processing power grows.
Tensions between the companies have grown over OpenAI’s plan to become a for-profit business. Negotiations have stalled over how much equity Microsoft will hold and what access it will retain to future AI models.
Charles Lamanna, a Microsoft executive, leads the Anthropic integration. CEO Satya Nadella recently promoted Lamanna to oversee business applications, including Copilot.
Microsoft has already diversified beyond OpenAI in other products. GitHub Copilot offers multiple AI models, including Anthropic’s Claude. The company also develops its own AI models and has integrated China’s DeepSeek into its Azure cloud platform.
OpenAI faces its own challenges, with plans to go public delayed until at least 2026 due to regulatory scrutiny and restructuring negotiations. The company also launched a jobs platform that competes with Microsoft’s LinkedIn.
Both OpenAI and Anthropic are developing workplace tools that directly compete with Microsoft’s software.
The shift reflects how AI companies are competing on specific, practical skills rather than just overall power. For Microsoft, choosing the best-performing model for each task matters more than keeping exclusive partnerships.