Anthropic has acquired Stainless, a developer tools startup known for its automatic SDK generation, previously used by AI giants like OpenAI and Google. The acquisition, with an undisclosed price, transitions Stainless's tools from general-purpose services to Anthropic's internal capabilities. Stainless, founded in 2022, was backed by Sequoia Capital and Andreessen Horowitz. Stainless's core product automatically generates and maintains SDKs, supporting languages such as Python and Java, and reduces manual maintenance by updating SDKs with API changes. Following the acquisition, Anthropic will phase out Stainless's hosted products, impacting companies like OpenAI and Cloudflare, which will lose access to these tools. This move highlights a trend of AI firms internalizing key development resources.