Anthropic is in advanced talks to acquire Stainless, the developer-tools startup whose software generates the SDKs used by OpenAI, Google and a roster of other AI companies, The Information reported. The deal would value the roughly four-year-old startup at at least $300 million, according to the report. Neither company has publicly confirmed the talks, and the terms could still change.
The potential acquisition is the latest sign that the biggest AI labs increasingly see the developer surface around their models — not just the models themselves — as strategic territory worth buying.
What Stainless builds
Stainless was founded by Alex Rattray, who previously architected Stripe's client-library code-generation system. The company's core product is a compiler that ingests an API specification and automatically produces "type-safe, quality SDKs in minutes instead of months," generating client libraries across languages including Python, TypeScript, Go and Kotlin.
More recently, Stainless extended the same approach to the Model Context Protocol, generating "code-mode" MCP servers from OpenAPI specs so AI agents can call an API's SDK and documentation rather than juggling dozens of raw endpoint schemas. That positioning — making APIs reliably usable by autonomous agents — sits squarely in Anthropic's wheelhouse, given that Anthropic originated MCP and has pushed it as an open standard.
Stainless's customer list reportedly includes OpenAI, Anthropic itself, Google, Meta's Llama Stack, LangChain and Groq. The company raised roughly $28 million in total, including a $25 million Series A led by Andreessen Horowitz in December 2024 with participation from Sequoia, Felicis, The General Partnership, Zapier and MongoDB. Its annual recurring revenue was reported to be hovering around $1 million, with the company said to be nearing profitability.
Why Anthropic wants it
Anthropic has been steadily acquiring infrastructure that sits underneath its Claude products. In December 2025 it bought Bun, the JavaScript runtime, to accelerate Claude Code, which the company says reached roughly $1 billion in run-rate revenue. Buying Stainless would give Anthropic direct control over how its own SDKs and MCP servers are produced — and, awkwardly for rivals, over a vendor that several competitors rely on.
The obvious tension: if Anthropic owns the tool OpenAI and Google use to ship their developer libraries, those companies may look for alternatives. Stainless's value has rested partly on being a neutral, multi-lab supplier; an acquisition by one lab tests that neutrality.
The bigger picture
The deal — if completed — fits a broader 2026 pattern of AI labs racing to own the agent stack end to end, from chips and clouds down to the API tooling developers touch every day. For Anthropic, fresh off reports of a $30 billion-plus funding round at a $900 billion-plus valuation, a $300 million tuck-in is a rounding error that could pay outsized dividends in developer lock-in.
