Inside Silicon Valley’s Love-Hate Relationship With Anthropic

In 2025, when AI startup Spellbook signed a long-term deal with Anthropic to use its models to review legal contracts, CEO Scott Stevenson wasn’t worried about the AI giant coming for his lunch. Anthropic staffers told him explicitly they didn’t see the firm directly competing with Spellbook in the legal space, he recalls.

A year later, he was caught off guard when Anthropic informed him that it was launching Claude for Legal. The tool, tailored for law firms, has dozens of capabilities ranging from contract review to citation checking to tracking regulatory changes — many of which overlap with Spellbook. That made things, “a little bit awkward,” Stenvenson says. He decided to be more cautious sharing data and product roadmaps with the AI giant.

“Anthropic has been a great partner but it made us realize that they are a massive company and two parts of the org can have conflicting mandates,” he says. “Ultimately this is inevitable.” Up until recently, Spellbook used Claude to carry out over 500,000 monthly contract reviews for its customers, but it’s now moved a lot of its spend to OpenAI.

Spellbook is far from the only company navigating a tricky relationship with Anthropic. A large swathe of startups relies on the AI behemoth for its top-tier models, widely considered among the best in the industry. But Anthropic’s dominance and aggressive expansion has led some of its customers to feel as if they are walking a tightrope. At any time, the AI company could train its models to directly compete with their own products.

One startup founder compared the dynamic to how Amazon started undercutting its vendors and manufacturing its own competitive products through Amazon Basics. “It’s like, yeah, for a while you can sell on Amazon, but then Amazon is going to start selling a version of your product too,” he says. Anthropic declined to comment.

If we build our business on just Anthropic’s models, we won’t be able to make money ever.