On Monday, Anthropic announced its acquisition of Stainless, a startup co-founded by ex-Stripe engineer Alex Rattray, known for its widely utilized software in rival AI labs, including OpenAI and Google.
While the financial details of the acquisition were not disclosed, a recent report from The Information indicated that Anthropic was negotiating a purchase of Stainless for over $300 million.
This strategic acquisition removes a vital infrastructure resource from Anthropic's competitors. Anthropic has informed TechCrunch that it plans to discontinue all hosted Stainless products, which include its software development kit (SDK) generator. Nevertheless, an Anthropic representative clarified that existing Stainless customers will retain ownership of the SDKs they’ve developed and will have the freedom to modify and enhance them as they see fit.
Founded in 2022 and based in New York, Stainless gained attention in the burgeoning AI sector for its automated approach to creating and maintaining SDKs—essential libraries that developers utilize to work with APIs. Rattray’s platform is designed to convert API specifications into production-ready SDKs across a variety of programming languages, including Python, TypeScript, Kotlin, Go, and Java. Its popularity stems from its ability to automatically update SDKs in response to changes in APIs, significantly reducing the time developers spend on manual maintenance.
This technology is particularly beneficial for organizations like Anthropic, OpenAI, Google, Replicate, Runway, and Cloudflare, which are developing AI agents capable of interfacing with external software to perform tasks on users' behalf. Previously accessible SDK tools from Stainless now become exclusive to Anthropic, effectively cutting off access for its competitors.
According to Anthropic, the Stainless software has been instrumental in generating every official SDK for Anthropic since the launch of its API.
Rattray expressed his vision for Stainless in a press release, stating, "I started Stainless because SDKs deserve as much care as the APIs they wrap. Anthropic was one of the first teams to support our mission. We have closely followed how developers have engaged with Claude in recent years, making this collaboration a seamless choice. Our team can continue our passion on a platform that truly matters."


