Anthropic Announces Acquisition of Stainless, the Standard for Auto-Generating SDKs from API Specifications. Who is CEO Alex Rattray?

On May 18, 2026, Anthropic announced its acquisition of Stainless, a startup that effectively holds the de facto standard in automated SDK generation for APIs. SDKs generated by Stainless are relied upon across the entire AI industry, including competitors such as OpenAI and Google, and Anthropic has stated that it will phase out the hosted product. While the acquisition price was not disclosed, The Information reported that negotiations were in the range of over $300 million. This article takes a multifaceted deep dive into how Stainless works and its technical advantages, the upbringing and career of CEO Alex Rattray, how Silicon Valley VCs are receiving the news, and the implications for OpenAI.