Anthropic acquires Stainless

The frontier of AI is shifting from models that answer to agents that act—and agents are only as capable as the systems they can reach. Today, Anthropic is acquiring Stainless, a leader in SDKs and MCP server tooling, to extend that reach even further.

Founded in 2022, Stainless has powered the generation of every official Anthropic SDK since the earliest days of our API. Hundreds of companies rely on Stainless to generate SDKs, CLIs, and MCP servers—the libraries, command-line tools, and connectors that let developers and agents use an API. Stainless turns an API spec into SDKs across TypeScript, Python, Go, Java, Kotlin, and more. Each one is fast, reliable, and built to feel native in its language.

"Stainless has shaped how developers experience the Claude API since the start, and it’s been great to work with them on that," said Katelyn Lesse, Head of Platform Engineering at Anthropic. “Agents are only as useful as what they can connect to. We’re excited to bring the Stainless team into Anthropic to advance Claude’s ability to connect to data and tools.”

"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," said Alex Rattray, founder and CEO of Stainless. "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."

Anthropic created MCP to make agent connectivity possible. By bringing together the Stainless and Anthropic teams, the Claude Platform continues to push the frontier of developer experience and agent connectivity.