Justin
Farr-Jones
I finance, build and fix companies.
Deal-led co-founder and operator. Thirty years across private equity, emerging markets, fintech and AI, from €2 billion of leveraged buyouts to the board of the company behind one of TypeScript's most-used libraries. Based in London.
Thirty years, by capital
Each line is a role. The figure is the capital I was responsible for or raised. Select a line for the detail.
Now
- Non-Executive Director, Effectful Technologies
- The Effect TypeScript library was incubated and funded at my fintech, Creditscript, led by our then CTO Michael Arnaldi, and open-sourced, building on fp-ts. Effectful, backed by Amplify Partners and Heavybit, now carries it forward; the library exceeds 60 million weekly downloads.
- Building agentic AI
- Advising clients on agent systems and prototyping them myself in TypeScript, Python and Rust: memory stores, security and agent-to-agent frameworks.
- Looking for the next company
- A co-founder seat at a well-funded AI, fintech or proptech company, an operating role at a PE-backed business, or a transaction mandate. See how I can help.
Writing
- Hire contractors, not employees: why A2A and ephemeral workers are the future of AI agentsAn opinion. The winning agent architecture will not be one all-knowing assistant with standing access. It will be short-lived, single-purpose workers that talk to each other through open protocols.
- Can a company trust its data to Anthropic or OpenAI? Ask where the memory livesThe model providers' contracts answer the training question. The bigger question is who owns your AI's memory and context, because that is where the intellectual property now sits.
- The harness half-life: AI is now moving faster than you can build for itThe machine-learning era took eight years. The agentic era has taken about twenty-four months. What that compression means for builders, boards and investors.