Anthropic announced Monday it has acquired Stainless, a developer tools startup that automates SDK generation and maintenance, in a deal reportedly worth more than $300 million according to The Information.

Founded in 2022 by former Stripe engineer Alex Rattray, Stainless has powered SDK generation for major AI companies including OpenAI, Google, Cloudflare, Replicate, and Runway. The New York-based startup, backed by Sequoia Capital and Andreessen Horowitz, converts API specifications into production-ready SDKs across multiple programming languages including Python, TypeScript, Go, Java, and Kotlin.

Many technology companies, AI labs included, relied on Stainless to build precisely the sorts of infrastructure that enables AI agents to connect to external data sources and tools. As a result of the acquisition, Anthropic will make this critical infrastructure-building service unavailable for its competitors: both companies have already confirmed that starting Monday, all Stainless hosted products will be winding down, including the SDK generator. Existing Stainless customers will retain full ownership of any SDKs they've already generated, and will be free to modify and extend them as they wish.

According to Stainless' announcement, the motivation behind the decision to wind down Stainless' hosted products responds to a shift in focus: Stainless will prioritize building out Anthropic's platform to develop new capabilities and ways to connect agents to APIs. "Agents are only as useful as what they can connect to," said Katelyn Lesse, Head of Platform Engineering at Anthropic. "We're excited to bring the Stainless team into Anthropic to advance Claude's ability to connect to data and tools."