Anthropic announced on Monday its acquisition of Stainless, a pioneering startup founded by former Stripe engineer Alex Rattray. Stainless's software has gained widespread adoption among prominent AI research labs, including competitors such as OpenAI and Google, for its innovative capabilities.
While Anthropic chose not to disclose the financial terms of the transaction, The Information reported last week that discussions were underway for a deal valuing Stainless, backed by venture capital giants Sequoia Capital and Andreessen Horowitz, at over $300 million.
This strategic acquisition effectively removes a critical infrastructure provider from the reach of Anthropic’s rivals. The company informed TechCrunch that it intends to discontinue all hosted Stainless products, including its popular SDK generator. However, an Anthropic spokesperson clarified that existing Stainless customers will retain full ownership of the SDKs they have generated to date, along with complete rights to modify and extend them as they see fit.
Founded in 2022 and based in New York, Stainless rapidly ascended within the burgeoning AI industry by specializing in the automated creation and maintenance of software development kits (SDKs). These essential libraries enable developers to seamlessly interact with application programming interfaces (APIs).
Rattray's ingenious software solution was designed to transform API specifications into production-ready SDKs across a diverse range of programming languages, including Python, TypeScript, Kotlin, Go, and Java. Its popularity stemmed from the platform's ability to automatically update SDKs in response to API changes, thereby eliminating the traditionally time-consuming and manual process of maintenance.
This technology holds particular value for companies like Anthropic, OpenAI, Google, Replicate, Runway, and Cloudflare, which are actively developing AI agents capable of connecting to external software and executing tasks on behalf of users. Stainless’s SDK tools offer an efficient method for building and maintaining these crucial connections. Moving forward, however, these indispensable tools will be exclusively available to Anthropic, no longer to its competitors.
Anthropic confirmed that Stainless software has been instrumental in generating every official Anthropic SDK since the inception of its API, underscoring a long-standing and foundational partnership.
“I started Stainless because SDKs deserve as much care as the APIs they wrap,” Rattray stated in a press release issued Monday. He added, “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.”
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