Anthropic has acquired developer infrastructure startup Stainless, a company whose software has been widely used by AI firms including OpenAI and Google to build and maintain software development kits for their APIs.
The companies did not disclose financial terms of the acquisition. However, The Information reported last week that Anthropic was negotiating to acquire Stainless for more than $300 million.
The deal removes a key infrastructure provider from the broader AI market and places its technology exclusively under Anthropic’s control.
Anthropic told TechCrunch it plans to shut down all hosted Stainless products, including the company’s SDK generator platform.
An Anthropic spokesperson said existing Stainless customers will retain ownership of SDKs already generated through the platform and will continue to have the right to modify and extend those tools independently.
Stainless Built SDK Automation Tools Used Across AI Industry
Stainless was founded in 2022 in New York City by former Stripe engineer Alex Rattray.
The startup became known within the AI industry for software that automates the creation and maintenance of software development kits, commonly known as SDKs.
SDKs allow developers to connect applications and services to APIs.
Rattray’s system converted API specifications into production-ready SDKs across multiple programming languages, including Python, TypeScript, Kotlin, Go, and Java.
The platform also automatically updated SDKs whenever APIs changed, reducing the need for companies to manually maintain integrations.
That capability became increasingly valuable as AI companies rapidly expanded APIs for models, agents, and developer tools.
Stainless software was reportedly used by companies including OpenAI, Google, Replicate, Runway, and Cloudflare.
Anthropic Expands Control Over AI Agent Infrastructure
The acquisition strengthens Anthropic’s position in AI infrastructure and developer tooling as competition intensifies around AI agents capable of interacting with external software systems.
Companies building AI agents increasingly rely on SDKs to maintain stable integrations between AI systems and external applications.
According to Anthropic, Stainless technology has powered every official Anthropic SDK since the company first launched its API offerings.
By bringing Stainless in-house, Anthropic gains direct control over a technology layer that many competing AI companies had previously depended on.
Going forward, Anthropic said the hosted Stainless tooling will no longer remain available to competitors.
Founder Says Anthropic Was Early Supporter
In a statement released Monday, Rattray said Anthropic had been among the earliest companies to adopt Stainless technology.
“I started Stainless because SDKs deserve as much care as the APIs they wrap,” Rattray said.
“Anthropic was one of the first teams to bet on this with us. We have been watching what developers have built on Claude over the last few years, which made bringing our teams together an easy decision,” he added.
The acquisition continues a broader trend of AI companies purchasing infrastructure startups that support model deployment, developer tooling, and agent ecosystems as competition expands beyond model performance alone.
Featured image credits: Heute.at
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