Fractional CTO · latest note →

I'm Ben Milleare.
A CTO with £1Bn of payments behind me.

I've spent twenty-five years in payments and infrastructure, and more recently focus on agentic AI and web3. This is where the work gets written down: what I'm shipping and what hard things I'm solving.

01Notes

Latest from
the field.

  1. 12Is the 10x engineer still a thing?

    A CTO friend can no longer pick out the 10x engineers on his team, because agentic coding has turned every capable engineer into one.

  2. 11438 million wallets, one app update

    Stripe already owns stablecoin issuance, wallets, and a chain. Buying PayPal would put 438 million funded accounts one app update from Web3.

  3. 10Never double-charge: the UPDATE is the lock

    Fixed Temporal workflow IDs, an UPDATE that doubles as a lock, and fail-closed reconciliation: layering double-charge protection into a payments system.

  4. 09Does every CTO need a skunkworks?

    With agentic teams, two hackers can spin up five MVPs while a normal team ships one feature. The case for keeping a skunkworks in your back pocket.

  5. 08Containment beats permission

    Coding agents should run unsupervised, but inside a dev environment that's safe to be wrong in. The agent boundary is the wrong line to defend.

  6. 07Let the price do the migration

    Most companies run a migration campaign to clear users off a deprecated API. Anthropic just tripled the price of theirs and let market forces do the work.

All 12 notes →

03Cross-domain

Most CTOs come up
through one discipline.

I came up through four, and the useful part has never been any one of them on its own. It is the squares where they meet, because that is where the expensive mistakes get made and where, in most companies, nobody is holding the whole picture at once.

domain ×
Technology
AI
Finance
Business
Technical strategy
Architecture chosen for the company you actually are
AI that pays
Business cases that survive a board meeting
Unit economics
What a transaction costs before anyone argues about it
Technology
Core engineering
Cloud, distributed systems, durable execution
Agents in production
Delegation, orchestration, containment
Payment systems
Rails, idempotency, reconciliation
AI
Model operations
Deploying, observing and versioning what ships
Core AI
LLMs, retrieval, multi-agent systems
Risk modelling
Decisions a regulator can follow afterwards
Finance
Reading a codebase
Telling an asset apart from a liability
Cost of inference
What a token really costs at volume
Core finance
Risk, compliance, a P&L I have carried myself
04About

Who is writing
this.

I have been building software for twenty-five years and leading the teams that build it for fifteen of those, mostly as a CTO across payments and infrastructure, and in crypto since 2013. Most of my attention now goes on AI systems and the unglamorous engineering that makes them dependable enough to put in front of customers.

05Book
The First-Time CTO · Coming soon

A field guide for new
technical leaders.

Twenty-five years of building, scaling, and selling technology companies, distilled into the practical playbook I wish someone had handed me about a decade ago. Selected chapters serialised on Notes ahead of release.

The First-Time CTO - 3D book mockup
06Elsewhere

Where else
I spend time.

  1. → Agentics Foundation associate

    I'm a member of the Agentics Foundation, the global community shaping safe, autonomous multi-agent AI, so your team gets first-look access to emerging patterns, governance standards, and production-grade orchestration tooling.