Anthropic · 2026-05-18 · major
Anthropic Acquires Stainless — Maker of the SDK, CLI, and MCP-Server Generator Behind Every Official Claude SDK
Anthropic has closed its acquisition of Stainless, the developer-tools startup whose code generator has powered every official Anthropic SDK since the Claude API launched. The team joins to improve how Claude connects to data and tools.
Anthropic buys the company that has generated every official Claude SDK since day one.
Key specs
| Reported price | $300M+ |
|---|---|
| Stainless last valuation | $150M (Dec 2024) |
| Stainless founded | 2,021 |
| Source outlet | The Information |
What is it?
Stainless, founded in 2022, builds tooling that generates SDKs, CLIs, and MCP servers from an API specification across TypeScript, Python, Go, Java, Kotlin, and more. It has powered every official Anthropic SDK since the Claude API launched and serves hundreds of other companies. Anthropic has now acquired the company outright.
How does it work?
Stainless takes an API specification and produces idiomatic client libraries and Model Context Protocol servers in many languages, keeping them in sync as the API changes. Inside Anthropic, the team will focus on Claude's agent connectivity — how the model reaches external data and tools.
Why does it matter?
Agents are limited by what they can connect to. Bringing Stainless in-house gives Anthropic direct control of the SDK and MCP-server tooling layer developers use to wire Claude into their systems, and signals deeper investment in MCP as the connection standard.
Who is it for?
developers building on the Claude API