Why Microsoft Adds Anthropic to Office 365 Alongside OpenAI

Microsoft will pay to use Anthropic’s technology for some AI features in Office 365 applications, changing from its previous reliance solely on OpenAI for workplace productivity tools.

The software giant plans to blend Anthropic and OpenAI technology in its Office apps after years of primarily using OpenAI models for features in Word, Excel, Outlook and PowerPoint. 

This is a shift in strategy for Microsoft, which has invested more than US$13bn in OpenAI and served as the ChatGPT maker’s biggest financial backer, according to Reuters.

Behind Microsoft’s switch

The decision comes as Microsoft seeks to diversify its AI portfolio amid growing demand for AI capabilities across enterprise software. 

The company is simultaneously developing its own AI models while integrating other providers’ technology, including DeepSeek models into 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.

However, developers working on Office AI features have found that Anthropic’s models outperform OpenAI in specific areas. 

These include automating financial functions in Excel and generating PowerPoint presentations based on user instructions, according to sources involved in the development effort.

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 is one of Anthropic’s largest shareholders and provides infrastructure for many of the startup’s services.

Anthropic was founded by former OpenAI executives and has positioned itself as a competitor to ChatGPT with its Claude family of large language models. 

These AI systems, trained on vast amounts of text data, can generate human-like responses and power applications from chatbots to content generation tools.

The integration comes as OpenAI prepares to launch GPT-5, its next-generation model. 

While GPT-5 represents a step up in quality from previous versions, Anthropic’s Claude Sonnet 4 performs better in creating PowerPoint presentations that are more aesthetically pleasing, according to development sources.

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 gained an early advantage in the AI race through its exclusive access to OpenAI’s models, giving it a head start over competitors like Google, which has integrated its own Gemini AI models into workspace applications.

Now Microsoft’s approach mirrors broader industry trends as companies seek to avoid dependence on single AI providers. 

Many enterprises are adopting strategies that combine different AI systems optimised for specific tasks rather than relying on one provider for all applications.

The integration affects Office 365, Microsoft’s subscription-based productivity suite used by hundreds of millions of workers worldwide.