Anthropic buys AI developer tools startup Stainless
19 May 2026, 11:13 AMWhile financial details were not officially revealed, reports suggest the deal could be worth more than $300 million.
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AI company Anthropic has acquired developer tools startup Stainless, a platform widely used by major tech firms such as OpenAI, Google, and Cloudflare.
While financial details were not officially revealed, reports suggest the deal could be worth more than $300 million.
Founded in 2022 by former Stripe engineer Alex Rattray, Stainless became well known for software that automatically creates and updates SDKs -- developer toolkits that help applications connect with APIs.
The acquisition gives Anthropic control over a critical piece of infrastructure used across the AI industry. The company said it will discontinue hosted Stainless products, including its SDK generation platform. Existing customers will still retain ownership of the SDKs they previously created and can continue modifying them independently.
Stainless technology has been especially useful for companies building AI agents capable of interacting with external software and services. Besides Anthropic, firms like OpenAI, Google, Replicate, Runway, and Cloudflare had relied on the startup’s tools to maintain these integrations more efficiently.
Anthropic said Stainless has powered its official SDKs since the early days of the company’s API platform. Rattray stated that joining Anthropic felt like a natural fit after seeing how developers were building applications around Claude and Anthropic’s ecosystem.
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