Stainless is a New York-based developer-tools startup, founded in 2022, whose software automates the generation and maintenance of software development kits (SDKs) for API providers. Its tooling was used across the AI industry by OpenAI, Google, and Cloudflare in addition to Anthropic. On May 18, 2026, Anthropic acquired the company; terms were not disclosed, though The Information had reported that talks involved $300 million or more (Source: techcrunch.com).
| Field | Value | |
|---|---|---|
| Type | Developer-tools startup (SDK generation automation) | |
| Founded | 2022 | |
| HQ | New York, NY | |
| Founder/CEO | Alex Rattray (former Stripe engineer) | |
| Pre-acquisition investors | Sequoia Capital, Andreessen Horowitz | |
| Current status (May 2026) | Acquired by [[anthropic | Anthropic]] May 18, 2026 (terms undisclosed; The Information had reported $300M+ in advance talks) |
Business
Stainless automates the creation and maintenance of software development kits (SDKs) — the libraries developers use to interact with APIs. Its software was used in the AI industry by OpenAI, Google, and Cloudflare, in addition to Anthropic, spanning competing frontier-model providers (Source: techcrunch.com).
The company was founded in 2022 by Alex Rattray, a former Stripe engineer, and is headquartered in New York. Before the acquisition its investors included Sequoia Capital and Andreessen Horowitz (Source: techcrunch.com).
Acquisition by Anthropic
Anthropic acquired Stainless on May 18, 2026. The terms were not disclosed; The Information reported that advance talks involved $300 million or more (Source: techcrunch.com). The acquisition came as Anthropic's Claude Code, Claude Cowork, and OpenClaw agentic products increased API consumption across customer integrations, raising the demand on SDK generation for partner developers (Source: techcrunch.com). It fits a broader pattern of Anthropic acquisitions and partnerships in May 2026 aimed at internalizing infrastructure that shapes partner developer experience (developer experience; Source: techcrunch.com).
Relationships
- regulated-by: (none — pre-revenue scale, no specific regulator)
- related: Anthropic, AI Acquihires, AI Coding Agents, Claude Code