Behind Microsoft's Move to Add Anthropic to Office 365

Microsoft will begin paying to integrate Anthropic’s technology into select AI features within Office 365, marking a move away from its previous exclusive reliance on OpenAI for productivity tools.

The company intends to combine Anthropic and OpenAI models across Word, Excel, Outlook and PowerPoint, diversifying after years of leaning primarily on OpenAI systems.

This represents a strategic adjustment for Microsoft, which has already invested more than US$13bn in OpenAI, becoming the ChatGPT developer’s largest financial supporter, Reuters reports.

Behind Microsoft’s switch

Microsoft’s move reflects its push to broaden its AI portfolio as enterprise demand for advanced capabilities accelerates.

Alongside its own model development, the company is also incorporating technology from other providers, such as DeepSeek, within its Azure cloud platform.

“As we’ve said, OpenAI will continue to be our partner on frontier models and we remain committed to our long-term partnership,” a Microsoft spokesperson says, according to Reuters.

Developers building AI features for Office have discovered that Anthropic’s models deliver stronger performance than OpenAI in certain use cases.

These advantages are most evident in automating financial tasks within Excel and creating PowerPoint presentations from user prompts, sources close to the development confirm.

AWS’ role in Microsoft’s plans

Microsoft will access Anthropic’s models by paying Amazon Web Services (AWS) rather than working directly with the AI company. 

AWS ranks among Anthropic’s largest investors and supplies the infrastructure underpinning much of the company’s services.

Founded by former OpenAI executives, Anthropic has emerged as a rival to ChatGPT with its Claude family of large language models, trained on extensive text data to power applications from conversational agents to content generation tools.

The latest integration coincides with OpenAI’s upcoming launch of GPT-5, positioned as a leap in capability over previous releases.

Yet, according to development sources, Anthropic’s Claude Sonnet 4 has shown stronger results in producing more visually polished PowerPoint presentations.

Microsoft’s dual-provider strategy

The addition of Anthropic technology doesn’t replace Microsoft’s OpenAI partnership but expands the company’s AI capabilities. 

Microsoft initially secured an edge in the AI race through its exclusive access to OpenAI’s models, outpacing rivals such as Google, which has integrated its Gemini AI systems into workspace tools.

Now, Microsoft’s strategy reflects a wider industry shift toward reducing reliance on a single AI partner.

Increasingly, enterprises are blending multiple AI systems, each optimised for specific functions, rather than depending on a single provider.

This latest integration spans Office 365, Microsoft’s subscription-based productivity suite with a global user base of hundreds of millions.