About

I'm a software engineer and designer. I take ideas from zero to one: the first version on my own or with one other person, then the team that grows around it. I've done that in my own companies and inside much bigger ones, ING and On Deck among them. For the last few years that's mostly meant applied AI: the product, the model calls, the evals, the infrastructure and the brand. The coding agents are how I scale myself. I'm building Fibers, a way to coordinate and instrument fleets of them, and it's how I've shipped millions of lines of code this year.

I do my best work when there is a high degree of unknown about whether something is possible.

Some of that has been for other people's ventures, as a fractional CTO: get a first version in front of real users, then hire the team that takes it on. A handful of times an investor has asked me to read a codebase and meet the team before a Series A. That work is under NDA, so it isn't on this site.

The pattern over the years is that the first version I write tends to keep going. I wrote the first code at Oak National Academy in April 2020, and it served 120 million lessons that year. I prototyped Aila, Oak's AI lesson assistant, which tens of thousands of teachers now use.

I led Platform at On Deck as it grew from 30 people to 350, and before that came Makeshift, where Product Hunt started life as a prototype, and 3form, my first company, which won a Webby.

Right now I'm co-founder of Arcla, a real-time coaching app for sales calls, and fractional CTO to Assembly, a guidance platform for families of neurodivergent children that's being readied for the NHS.

Everything else I've made online since 1995 is on this site, the dead things included. If any of it is useful to what you're building, or something here is wrong, write to hi@stef.io.