John Kattenhorn in a black T-shirt, arms folded, smiling, against a dark studio backdrop.

Always. Building. Something.

John Kattenhorn Chief Technology Officer

I lead technology teams and build alongside them.

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On the bench.

More in the Build Log
A garage workshop: a pine workbench with drawers, a pegboard of yellow power tools on a dark grey wall, a drill press on the left and a red tool chest on the right.
My workshop.
A tall square frame of pale laser-cut plywood, slotted together, standing on a blue cutting mat.
A light frame I designed at 4R Digital. Laser-cut ply snaps together, so it can be made locally and cheaply from materials available in developing countries. It wasn't funded, but the client loved the design.
3D-printed parts laid out on a cutting mat and a wooden bench: six grey wheels, rows of grey brackets and gears, black suspension arms and a blue body shell.
Every printed part for the rover I'm building now, laid out before assembly.
Two identical black cube servers with slatted wooden fronts on a white desk, one on each side of a monitor, with a small network switch on top of the left one.
My homelab: two identical servers.
A green circuit board with a SIM card holder at one end, two chips in the middle and the Applicita logo at the other end.
A modem board for the Meadow F7. My team at Applicita designed it because we couldn't wait for the maker's own. It went into a carbon-displacement project that monitored the electricity used for electric cooking in Africa.
A CNC router with a yellow spindle and a black dust hose cutting a sheet of plywood, with a laptop on the bench beside it.
The CNC router, cutting.
Two Oric Atmos computers in their original polystyrene packaging, black with red keys, each beside its power supply and a Tansoft welcome booklet.
Two Oric Atmos. It was my first computer.
The Mandelbrot set rendered on an Oric Atmos: one bit per pixel, black and white, the chunky edges of a 1983 screen.
A Mandelbrot set on the Oric. An agent wrote the inner loop in 269 bytes of 6502, which made it about ten times faster than my BASIC.

Recent work

Four Jira skills

When agent adoption outran any shared answer, our engineers built their own. At the worst point there were four versions of one Jira skill. What it took to get back to one, and why I would do it first next time.

Leadership · 24 Sep 2026 · 8 min read

Blast radius

AI-assisted coding has moved the cost side of build against buy, and it keeps moving. What it has not moved is who is answerable when the thing fails. Four questions, four bands, and the guards that go with each.

Leadership · 18 Sep 2026 · 9 min read

A markdown editor an agent can type into

A fork of the editor Omarchy ships, with a D-Bus command line so a coding agent can change a file while it is open in front of me.

Build Log · 18 Sep 2026