Anthropic acquires Stainless in $300 million deal to secure AI agent infrastructure
The acquisition of New York-based developer tools startup Stainless strengthens Anthropic’s strategic shift toward autonomous agents, with existing customers retaining rights to generated software development kits.
Anthropic has acquired Stainless, a New York-based developer tools startup founded by former Stripe engineer Alex Rattray, in a transaction that removes a critical infrastructure supplier from the hands of its rivals. The deal, which reportedly values the company at more than $300 million according to a report by The Information last week, consolidates SDK generation capabilities for Anthropic and aligns with its broader strategy to transition from models that merely answer queries to agents that act.
Founded in 2022, Stainless rose to prominence in the artificial intelligence sector by automating the creation and maintenance of software development kits. The platform allows developers to convert API specifications into production-ready SDKs across multiple programming languages, including Python, TypeScript, Kotlin, Go, and Java. Crucially, the software automatically updates these kits as underlying APIs change, eliminating the manual maintenance burden that previously slowed development cycles for companies building AI agents.
The acquisition significantly alters the competitive landscape by withdrawing a key tool previously utilised by major competitors such as OpenAI, Google, and Cloudflare. Stainless software has powered the generation of every official Anthropic SDK since the earliest days of its API. By bringing the technology in-house, Anthropic aims to strengthen agent connectivity for its Claude platform, ensuring that its models can more effectively connect to external data and tools to complete tasks on behalf of users.
Katelyn Lesse, Head of Platform Engineering at Anthropic, emphasised the strategic importance of the move. “Agents are only as useful as what they can connect to,” Lesse said. “We’re excited to bring the Stainless team into Anthropic to advance Claude’s ability to connect to data and tools.” The company confirmed that Stainless will wind down all hosted products, including its SDK generator, as part of the integration process.
Despite the shutdown of hosted services, existing customers retain full rights to modify and extend the SDKs they have generated to date. Stainless, which is backed by Sequoia Capital and Andreessen Horowitz, was among the first teams to support the platform. Founder Alex Rattray noted that Anthropic was one of the earliest supporters of the venture, making the acquisition a natural progression for the team. The specific financial terms of the deal were not disclosed by Anthropic.
