Anthropic Acquires Stainless SDK Startup Used by OpenAI and Google

anthropic announced on Monday that it has acquired Stainless, a Developer Tools startup founded by former Stripe engineer Alex Rattray. StAInless is widely known for its software used by competing AI labs, including OpenAI and Google.

Financial terms of the deal were not disclosed. However, The Information reported last week that Anthropic was in talks to acquire Stainless — a company backed by Sequoia Capital and Andreessen Horowitz — for over $300 million.

The acquisition rEMOves a key infrastructure provider from the hands of Anthropic’s rivals. Anthropic told TechCrunch that it will wind down all hosted Stainless products, including its SDK generator. A company spokesperson confirmed that existing Stainless customers will retain full ownership of the SDKs they have already generated, along with complete rights to modify and extend them as needed.

Founded in 2022 and based in New York, Stainless quickly gained prominence in the AI industry by automating the creation and maintenance of software development kits (SDKs), the libraries developers use to interACT with APIs.

Rattray built software capable of converting API specifications into production-ready SDKs across multiple programming languages, including Python, TypeScript, Kotlin, Go, and Java. The platform gained widespread adoption because it automatically updates SDKs whenever APIs change, eliminating the tedious, time-consuming process of manual maintenance.

This Technology is especially valuable for companies like Anthropic, openai, google, Replicate, Runway, and Cloudflare, all of which are developing AI Agents that interact with external software to complete tasks on behalf of users. Stainless’s SDK tools provide an efficient way to build and maintain those connections — but going forward, the tools will be available exclusively to Anthropic.

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

“I started Stainless because SDKs deserve as much care as the APIs they wrap,” Rattray said in a press release on Monday. “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.”