Microsoft 365 Copilot and Redmond’s AI-powered tools in general have exclusively used OpenAI’s large language models (LLMs), primarily because of the multi-billion-dollar investments that Microsoft has made in Sam Altman’s company in the past six or so years. However, in a major turn of events, Redmond has now announced expanded model choices in some areas of its Microsoft 365 Copilot suite.
Some services in Microsoft 365 Copilot will offer integration with OpenAI rival Anthropic’s models starting today. The Researcher reasoning agent will be able to leverage either OpenAI’s deep reasoning models or Anthropic’s Claude Opus 4.1. This particular agent specializes in multi-step deep research.
Similarly, users will be able to select Claude Sonnet 4 and Claude Opus 4.1 in Copilot Studio, allowing for complex orchestration of agentic tasks. Customers also have the ability to mix and match specialized models from various vendors to perform multiple tasks.
It is important to note that Microsoft 365 Copilot itself will continue to be powered by OpenAI, but the shift in strategy is certainly interesting. Microsoft’s President of Business & Industry Copilot Charles Lamanna had the following to say regarding the decision:
Copilot will continue to be powered by OpenAI’s latest models, and now our customers will have the flexibility to use Anthropic models too—starting in Researcher or when building agents in Microsoft Copilot Studio. The addition of Claude Sonnet 4 and Claude Opus 4.1 advances our commitment to bring the best AI innovation from across the industry to Microsoft 365 Copilot, tuned for work and tailored to your business needs.
Keep in mind that while OpenAI’s models are hosted on Microsoft Azure, Anthropic’s models are hosted on AWS. Claude in Researcher is available today for Frontier Program customers for Microsoft 365 Copilot customers, while the same and other Anthropic models are available for firm users who opt-in to the experience. Microsoft has committed to bringing Anthropic’s models to even more Microsoft 365 Copilot experiences in the future.