Krux
May 20, 2026
Anthropic Buys SDK Maker Used by OpenAI and Google
Published: May 20, 2026 at 12:12 AM
Updated: May 20, 2026 at 12:12 AM
100-word summary
Anthropic acquired Stainless, the developer-tools startup that builds SDKs for OpenAI, Google, and Cloudflare, for more than $300 million according to The Information. The move pulls critical tooling in-house while shutting down Stainless' hosted products. Existing customers keep their SDKs, but competitors lose access to future SDK automation from a vendor they relied on. Stainless already generated every official Claude SDK since its 2022 founding. The acquisition signals Anthropic is betting that controlling the plumbing between AI models and developer apps matters as much as the models themselves.
What happened
Anthropic acquired Stainless, the developer-tools startup that builds SDKs for OpenAI, Google, and Cloudflare, for more than $300 million according to The Information. The move pulls critical tooling in-house while shutting down Stainless' hosted products. Existing customers keep their SDKs, but competitors lose access to future SDK automation from a vendor they relied on. Stainless already generated every official Claude SDK since its 2022 founding.
Why it matters
The acquisition signals Anthropic is betting that controlling the plumbing between AI models and developer apps matters as much as the models themselves.