Anthropic acquires Stainless
Stainless had generated every official Anthropic SDK since the company's early days; terms were not disclosed, though outside reporting put the deal above $300 million.
- Money & business
- Minor
Anthropic acquired Stainless, a startup that generates SDKs, command-line tools and MCP server connectors from API specifications across languages including TypeScript, Python, Go and Java. Stainless, founded in 2022, had powered the generation of every official Anthropic SDK since the company’s early days, and hundreds of other companies relied on its platform to build their own developer tooling.
Anthropic did not disclose financial terms, though outside reporting put the deal above $300 million. The company framed the acquisition around agent capability rather than developer convenience alone: Katelyn Lesse, its head of platform engineering, said “agents are only as useful as what they can connect to,” positioning the purchase as an investment in how well Claude and Claude-based agents could integrate with external tools and data sources. Stainless’s chief executive, Alex Rattray, said the fit reflected Anthropic having been “one of the first teams to bet on” the idea that SDKs deserved as much engineering care as the APIs they wrapped.
The acquisition folded a piece of shared developer infrastructure — one used by rival labs’ customers as well as Anthropic’s own — into a single company’s product line, a pattern that recurred through 2026 as frontier labs bought up tooling and infrastructure companies to control more of the agent stack directly.