Startups & Funding
Anthropic buys Stainless, will wind down competitor access
Anthropic has acquired New York-based dev tools startup Stainless in a deal reportedly valued at more than $300 million, planning to wind down the startup's hosted products.
Anthropic announced Monday that it has acquired Stainless, a New York-based developer tools startup. The acquisition deal is reportedly valued at more than $300 million, according to reporting by The Information last week. While Anthropic did not disclose the financial terms of the transaction, the startup had previously raised backing from venture capital firms Sequoia Capital and Andreessen Horowitz. Following the transaction, Anthropic plans to wind down all hosted Stainless products.
Founded in 2022, Stainless built a reputation in the artificial intelligence sector by automating the creation and maintenance of software development kits, or SDKs—the libraries that developers use to interact with application programming interfaces, or APIs. The startup’s technology automated the process of turning API specifications into production-ready SDKs, eliminating the need for manual maintenance as APIs updated. These tools have been widely used by Anthropic’s competitors and customers, including OpenAI, Google, Cloudflare, Replicate, and Runway, to connect AI agents to external software and complete tasks on behalf of users. Stainless’s SDK tools provided an efficient way to build and maintain those connections—but going forward, the tools will only be available to Anthropic. According to Anthropic, Stainless software has powered the generation of every official Anthropic SDK since the earliest days of its API.
Alex Rattray, the founder of Stainless and a former employee of Stripe, started the company because he believed SDKs deserve as much care as the APIs they wrap. In a statement posted Monday, Rattray explained that Anthropic was one of the first teams to bet on the startup. He noted: “Anthropic was one of the first teams to bet on this with us. We have been watching what developers have built on Claude over the last few years, which made bringing our teams together an easy decision. The team gets to keep doing the work we love, on the platform where it matters most.”
Why it matters
This acquisition removes a key infrastructure supplier from the hands of Anthropic’s competitors, as the company plans to wind down all hosted Stainless products.