Anthropic has acquired the dev tools startup used by OpenAI, Google, and Cloudflare

Anthropic announced Monday that it has acquired Stainless, a startup founded by former Stripe engineer Alex Rattray whose software is widely used by rival AI labs including OpenAI and Google.

Anthropic did not disclose the terms of the deal. However, the information reported last week, Anthropic was in talks to acquire Stainless, which is backed by Sequoia Capital and Andreessen Horowitz, for more than $300 million.

The acquisition will remove an important infrastructure supplier from Anthropic’s competitors. The company told TechCrunch that it will phase out all hosted Stainless productsincluding the SDK generator. An Anthropic spokesperson said Stainless customers will still own the SDKs they have generated so far, and will have full rights to modify and extend them as they wish.

Founded in 2022, the New York-based startup rose to prominence in the emerging AI industry for automating the creation and maintenance of software development kits, or SDKs – the libraries developers use to interact with APIs.

Rattray developed software that could convert API specifications into production-ready SDKs in multiple programming languages, including Python, TypeScript, Kotlin, Go, and Java. It became a popular tool because the platform automatically updates the SDKs when APIs change, eliminating the time-consuming process of manually maintaining them.

The technology is particularly valuable for companies such as Anthropic, OpenAI, Google, Replicate, Runway, and Cloudflare that build AI agents that can connect to remote software and complete tasks on behalf of users. Stainless’ SDK tools are an easy way to build and maintain those connections – but in the future the tools will only be available to Anthropic, not its competitors.

According to Anthropic, Stainless software has enabled the generation of every official Anthropic SDK since the early days of its API.

“I started Stainless because SDKs deserve as much care as the APIs they package,” says Rattray in a press release posted on Monday. “Anthropic was one of the first teams to bet on this with us. We looked at what developers have built on Claude over the years, which made bringing our teams together an easy decision. The team can continue doing the work we love, on the platform where it matters most.”