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Geoffrey Greenfield, Founder and Director of Reuteri Limited
Founder & Director

Geoffrey Greenfield.

Founder and Director of Reuteri Limited — the small-batch maker behind The Sixth Strain, an Australasian-first multistrain probiotic coconut bio-ferment, made by hand in Whangārei, Northland.

He runs the company on one principle: do what's right, not what's easy — and let honest process show in the jar. Every batch, every supplier, every decision traces back to him. He is the maker, and the accountable hand behind the brand.

Reuteri is built in the open, with an unusual edge: a council of frontier AI models that pressure-tests his thinking — but never touches the food.

The Karpathy Council
High-performance synthetic intelligence, embedded in a real company — eleven frontier models, one in each board seat, pressure-testing every decision.
Meet the council ↓
The Council The Synthetic Brain The Stack Talk to Geoffrey The Science →

The Karpathy Council.
Eleven seats. One table.

Named for the engineer who first wired a "council" of AIs together — Andrej Karpathy — this is Reuteri's board of advisors. Eleven frontier AI models, each holding a seat and a remit. They take a question, argue it from every angle, and hand back a sharper answer than any one of them — or any one founder — would reach alone. They debate the hard calls. Geoffrey makes them.

Every seat here is an AI. The council advises — it does not ferment. Reuteri Bio-Ferment is made by hand by Geoffrey in Whangārei. The food is, and always will be, human-made.
Strategy
Chief Executive
Claude Opus 4.8

Holds the long game. Weighs every decision against where the company is trying to get to, and makes the final recommendation.

Finance
Chief Financial
GPT-4.1

Unit economics, cash runway, and the unglamorous question behind every idea: do the numbers actually work?

Research & Development
Head of R&D
Gemini 2.5 Pro

Fermentation, strains and product development — the scientific rigour behind what goes in the jar.

Marketing
Chief Marketing
Claude Sonnet 4.6

Brand, story and positioning — how The Sixth Strain earns attention honestly in a crowded market.

Operations
Head of Operations
Grok 4.3

Supply chain and production flow — sourcing, scheduling, and getting good jars made on time.

Digital & Content
Head of Digital
GPT-4.1

Website, content and the build-in-public story — how the work gets shown, not just done.

Legal & Compliance
Regulatory Advisor
Claude Sonnet 4.5

NZ food law and fair trading — the seat that keeps every word honest and every claim on the right side of the line.

Sales & Distribution
Head of Sales
Gemini 2.5 Flash

Channels, stockists and subscriptions — the routes that grow a real customer base, week by week.

Sustainability & Ethics
Head of Sustainability
Grok 4.20

Packaging, footprint and the ethics behind the product — keeping the company honest about its impact.

Customer Experience
Head of CX
Claude Opus 4.7

The customer's view — from first taste to repeat order, and everything that makes that journey worth it.

Lean Strategy
Independent Contrarian
GLM-5.2

The board's contrarian — pressure-tests every position for the simpler, leaner path, so the company builds what's right, not just what's easy.

The Synthetic Brain.
Watch it grow.

Everything Reuteri knows — products, strains, suppliers, decisions, the lot — lives in an Obsidian "second brain". This is the celestial map of it: every note a star, every link a thread of light. It is rebuilt from the brain at the close of each day, so as the company learns and grows toward market, the map changes shape.

For the tinkerers and the merely curious: drag it, spin it, follow the threads. Come back in a month and it will have grown.

Drag to rotate · scroll to zoom · or use the sliders below to explore.

View
Forces & look
Reuteri Synthetic Brain · refreshed at end of day Open full screen ↗

The live Synthetic Brain is an interactive 3D map — best explored on a laptop or desktop. Pop back on a bigger screen to drag, spin and zoom through it.

The stack behind it.
Nothing hidden.

None of this is secret. If you're curious — or want to build something like it yourself — here is everything wiring the AI system together, and where to find it.

The AI agent that builds and runs the whole system — this website, the council app, the brain. Made by Anthropic.
The frontier models
The council's eleven seats are real frontier AIs: Anthropic Claude, OpenAI GPT, Google Gemini, xAI Grok, and Zhipu GLM.
One doorway to every model — so eleven different AIs from five different labs can sit at the same table.
The "second brain" — every note, decision and source about Reuteri, linked together. The Synthetic Brain above is built directly from it.
Version control and private cloud backup — it lets the whole system run, update and be reached from anywhere.
The open-source board framework by Andrej Karpathy, rebuilt into Reuteri's ten-member advisory board.
The engine (built on Three.js) that renders the Synthetic Brain live in your browser.

Curious?

Want to know how it works?
Talk to Geoffrey.

Email the Director

Whether you're a tinkerer, a fellow founder, or just curious how advanced AI can sharpen a real business — Geoffrey is happy to talk.