Daily AI CatchupMicrosoft Is Quietly Replacing OpenAI and Anthropic With Its Own AI in Excel and Outlook
Microsoft has started routing Excel and Outlook prompts through its in-house MAI models rather than OpenAI or Anthropic. The economics are the driver: Microsoft consumes tokens at massive scale, gets a discount through equity deals set to expire, and Mustafa Suleyman is reportedly pushing to "ultimately eliminate" the Anthropic bill — the clearest signal yet that vertical integration, not just partnerships, is Microsoft's real AI strategy.
Why it matters
💻 Developer · If you build on Microsoft 365 Copilot APIs, be aware the underlying model may already be shifting from OpenAI/Anthropic to Microsoft's own MAI — worth testing for behavior differences.
📦 Product · Vertical integration by your platform partner is a recurring pattern worth planning around if your product depends on any single Big Tech AI partnership.
🎨 Design · No direct design impact — this is a backend model-routing change end users likely won't notice directly.
📈 Business · Microsoft's expiring equity-deal discounts creating a hard incentive to cut the Anthropic bill is a useful data point for understanding the economics behind Big Tech's AI partnerships — they're less permanent than they look.
🤔 Just Curious · Microsoft is swapping out the AI powering Excel and Outlook — from OpenAI and Anthropic's models to its own homegrown AI — mainly to save money as its special pricing deals expire.
Sources: Microsoft replaces OpenAI & Anthropic with own AI in some apps