Anthropic has acquired development 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 that Anthropic is in talks to acquire Stainless, backed by Sequoia Capital and Andreessen Horowitz, for more than $300 million.

The acquisition will take a major infrastructure supplier out of the hands of Anthropic’s competitors. The company told TechCrunch that it will discontinue all hosted Steel products, including its Generator SDK. An Anthropic spokesperson said Steel customers will still own the SDKs they’ve created so far, and have full rights to modify and expand them however they want.

The New York-based startup, founded in 2022, has risen to prominence in the emerging AI industry for automating the creation and maintenance of software development kits, or SDKs — libraries that library developers use to interact with APIs.

Rattray has developed software that can take API specifications and turn them into production-ready SDKs across multiple programming languages, including Python, TypeScript, Kotlin, Go, and Java. It has become a popular tool because the platform automatically updates software development kits (SDKs) as application programming interfaces (APIs) change, eliminating the time-consuming process of maintaining them manually.

This technology is especially valuable to companies like Anthropic, OpenAI, Google, Replicate, Runway, and Cloudflare that are building AI agents that can connect to external software and complete tasks on users’ behalf. The steel company’s SDKs are an easy way to build and maintain those connections — but from now on, the tools will only be available to Anthropic, not its competitors.

According to Anthropic, Stainless Steel Software has powered every official Anthropic SDK since the early days of its API.

“I started Steel because SDKs deserve as much attention as the APIs they wrap,” Rattray said in a press release published Monday. “The Anthropic team was one of the first teams to bet with us on this. We’ve been watching what developers have been building on Claude over the past few years, which made bringing our teams together an easy decision. The team should continue to do the work we love, on the platform where it matters most.”