Anthropic Acquires Stainless, the SDK and MCP Tooling Startup Used by OpenAI and Google
Anthropic
Anthropic announced the acquisition of Stainless, a New York-based startup (founded 2022) that built and maintained Anthropic's official SDKs since the earliest API days. The deal is reported at over $300 million. Stainless also built SDKs for OpenAI, Google, and Cloudflare. Anthropic plans to wind down all hosted Stainless products — including its third-party SDK generator — going forward, though existing customers retain full rights to already-generated SDKs. The acquisition is framed as a move to strengthen Claude's agent connectivity via the Model Context Protocol (MCP) ecosystem.
Why it matters
By bringing Stainless in-house, Anthropic secures a piece of AI infrastructure that both OpenAI and Google relied on, accelerates its own MCP/SDK roadmap, and removes a neutral third-party tooling provider from the ecosystem — a significant competitive play as agent connectivity becomes a key battleground.
Importance: 3/5
Strategic $300M acquisition removing a neutral AI tooling provider used by OpenAI, Google, and Cloudflare — notable industry consolidation in the MCP/SDK space