Anthropic announced Monday that it has acquired Stainless, a startup founded by former Stripe engineer Alex Rattray. The company’s software is widely used by rival AI labs, including OpenAI and Google.
Anthropic did not disclose terms of the deal, but The Information reported last week that the company was in talks to acquire Stainless, which is backed by Sequoia Capital and Andreessen Horowitz.
Anthropic: How does the acquisition of Stainless affect competitors?
The acquisition will remove a key infrastructure provider from Anthropic’s competitors. The company told TechCrunch that it will discontinue all hosted Stainless products, including the SDK generator. An Anthropic spokesperson said that Stainless customers will still own the SDKs they have built to date and will have full rights to modify and extend them as they wish.
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The New York-based startup was founded in 2022 and became known in the emerging AI industry for automating the creation and maintenance of software development kits or SDKs — the libraries that developers use to interact with APIs.
Rattray developed software that could take API specifications and turn them into production-ready SDKs in multiple programming languages, includingPython, TypeScript, Kotlin, Go, and Java. It became a popular tool because the platform automatically updates SDKs as APIs change, eliminating the time-consuming process of manually maintaining them.
The technology is particularly 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 behalf of users. Stainless’s SDK tools are an easy way to create and maintain those connections — but going forward, the tools will only be available to Anthropic, not its competitors. According to Anthropic, Stainless’s software has powered the creation of every official Anthropic SDK since the early days of its API.
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“I started Stainless because SDKs deserve the same care as the APIs they surround,” Rattray said in a press release published Monday. “Anthropic was one of the first teams to bet on this with us. We’ve been watching what developers have built at Claude over the past few years, which made combining our teams an easy decision. The team continues to do the work we love, on the platform where it matters most.”
Competition in the AI sector is growing
Anthropic’s acquisition of Stainless clearly demonstrates that competition in the AI space is no longer limited to AI models, but also extends to the critical infrastructure that supports the developer ecosystem. SDKs and APIs have become a key part of developing modern AI applications and agents, allowing companies to more quickly and efficiently integrate their services across different platforms. With this move, Anthropic acquires not only a technologically significant team, but also greater control over a tool that has been used to date by competitors such as OpenAI and Google.
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At the same time, the deal highlights the strategic importance of developer tools in the new era of AI. As companies increasingly invest in AI agents and automated services, the ability to quickly create and maintain secure connections to external APIs is becoming a critical competitive advantage. Anthropic’s decision to discontinue Stainless’s hosted products will likely force several companies to seek alternative solutions, while accelerating the creation of new tools and services in the market. The coming period is expected to be particularly interesting, as the major AI companies seem to be entering a new phase of the “infrastructure battle”, where the technology behind the models becomes as important as the AI models themselves.
