Anthropic Acquires AI Dev Tools Startup Stainless, Used by OpenAI and Google

Anthropic announced Monday that it has acquired Stainless, a startup founded by former Stripe engineer Alex Rattray. Stainless's software is widely used by rival AI labs, including OpenAI and Google. The acquisition takes a key infrastructure supplier out of the hands of Anthropic's competitors.

The terms of the deal were not disclosed, but The Information reported last week that Anthropic was in talks to acquire Stainless for more than $300 million. Stainless, backed by Sequoia Capital and Andreessen Horowitz, will see its hosted products wound down, including its SDK generator. However, customers will still own the SDKs they've generated to date and have full rights to modify and extend them.

Stainless, founded in 2022, rose to prominence in the emerging AI industry for automating the creation and maintenance of software development kits (SDKs). The company's technology can take API specifications and turn them into production-ready SDKs across multiple programming languages. This technology is particularly valuable to companies building AI agents that can connect to external software and complete tasks on behalf of users.

The acquisition means that going forward, Stainless's SDK tools will only be available to Anthropic, not its competitors. According to Anthropic, Stainless software has powered the generation of every official Anthropic SDK since the company's earliest days. Rattray said in a press release, "I started Stainless because SDKs deserve as much care as the APIs they wrap.

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."