The Biggest Brain in AI Just Picked a Side
Andrej Karpathy — OpenAI co-founder, former Tesla AI chief, and arguably the most recognisable AI researcher on the planet — announced Tuesday he’s joining Anthropic. Not returning to OpenAI, where he co-founded the company and worked twice. Not staying solo with Eureka Labs. Anthropic.
“I think the next few years at the frontier of LLMs will be especially formative,” Karpathy wrote. “I am very excited to join the team here and get back to R&D.”
He’s joining the pre-training team under Nick Joseph, with a mandate to build a new team focused on using Claude to accelerate pre-training research. That’s not a ceremonial title — that’s Anthropic signalling it believes AI-assisted research, not just raw compute, is the path to staying ahead.
And it came with a bonus: cybersecurity veteran Chris Rohlf also joined Anthropic’s frontier red team the same day.
The Stainless Move: Anthropic Now Owns OpenAI’s Infrastructure
Two days before Karpathy’s announcement, Anthropic acquired Stainless for over $300 million. If you’ve ever run pip install openai or used the Gemini Python library, Stainless generated that package. They make the SDKs for OpenAI, Google Gemini, Meta Llama, Cloudflare, and hundreds of other APIs.
Anthropic now owns the infrastructure its competitors depend on — and immediately shut down the hosted product. Existing customers retain rights to SDKs already generated, but the automated compiler that rebuilt packages whenever API specs changed is gone. OpenAI and Google now face a choice: rebuild SDK generation in-house (which they abandoned once already) or migrate to competitors like Speakeasy, LibLab, or Fern.
The strategic read is unmistakable. As Forbes put it: Anthropic is buying components that rivals also touch. Stainless is the fourth acquisition in six months — after Bun (JavaScript runtime), Vercept (computer-use), and Coefficient Bio (biotech). Each target was already used by Claude or its customers before acquisition.
This isn’t a model lab anymore. Anthropic is behaving like a platform company.
Meanwhile at OpenAI: All In on Brockman
While Anthropic was acquiring infrastructure, OpenAI was consolidating internally. Co-founder Greg Brockman has taken over product strategy, merging ChatGPT, Codex, and the Developer API into a single agentic platform under his leadership. The “super app” strategy kills side projects and focuses everything before an expected IPO.
The timing — four days before Google I/O — is not accidental.
OpenAI is betting that a unified desktop experience (ChatGPT + Codex + Atlas browser) can become the consumer gateway to AI. It’s a reasonable bet, but it’s also an admission: three separate products were confusing users and splitting engineering resources.
What This Means
For Anthropic: This week establishes them as the most strategically aggressive AI company on the planet. Karpathy gives them the most credible LLM researcher alive, and Stainless gives them infrastructure leverage over every competitor. The reported $800 billion valuation in talks isn’t hype — it’s the market pricing in platform dominance.
For OpenAI: Losing Karpathy (again) while your biggest rival buys the company that generates your SDKs is a brutal 48 hours. The unified product strategy under Brockman is the right move, but it’s reactive. OpenAI is consolidating because it has to, not because it chose to.
For developers: Stainless’s hosted product is gone. If you’re building on OpenAI or Gemini SDKs, the toolchain that auto-updated those packages is now maintained by a direct competitor. Time to evaluate alternatives.
For NZ: The AI industry’s consolidation has direct implications. When the SDK infrastructure you depend on is owned by one of the providers, vendor lock-in deepens. NZ companies building on OpenAI’s API should be reviewing their dependency chain this week.
🔍 THE BOTTOM LINE
The scattered experimentation era of AI is over. Karpathy chose Anthropic. Anthropic bought OpenAI’s infrastructure. OpenAI merged its products. Google’s investing $5 billion with Blackstone in compute. Everyone is picking a lane — and the lanes are narrowing fast. If you’re building on these platforms, the next 12 months will determine whose ecosystem you’re actually in.
❓ Frequently Asked Questions
Q: Why did Karpathy choose Anthropic over OpenAI? He said he wanted to “get back to R&D” at the frontier of LLMs. Anthropic’s pre-training team gave him that focus. At OpenAI, he’d left twice — once for Tesla, once to start Eureka Labs. The third time, he chose the competitor.
Q: What happens to Eureka Labs? Karpathy said he “remains deeply passionate about education and plans to resume my work on it in time.” That’s not a clear commitment. Eureka Labs hasn’t shared updates in months.
Q: Does Anthropic owning Stainless affect my OpenAI SDK? Not immediately. Existing packages stay on PyPI and npm. But the automated tool that kept them updated is gone. Over time, maintenance quality may diverge. OpenAI and Google will need to rebuild or replace.
Q: What should NZ companies do? Audit your AI dependencies now. If your stack depends on Stainless-generated SDKs, understand that the maintenance roadmap just changed. Consider alternatives, and don’t assume your provider’s infrastructure is vendor-neutral anymore.
📰 SOURCES
- TechCrunch — OpenAI co-founder Andrej Karpathy joins Anthropic’s pre-training team (19 May 2026)
- Forbes — Anthropic Buys The SDK Pipeline OpenAI And Gemini Depend On (19 May 2026)
- The Next Web — OpenAI merges ChatGPT and Codex under Greg Brockman (17 May 2026)
- Anthropic — Anthropic acquires Stainless (18 May 2026)
- UC Today — Anthropic Acquires Stainless, the SDK and MCP Startup (19 May 2026)
