Staff / founding engineer ·15 years ·full-stack & AI ·Minneapolis, MN

Tom Duffield

I build software for people.

Once I'm convinced something should exist, I don't stop until it does. It usually starts as something just for me, then grows into something others can use too.

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01What I've built

Trailhead coming soon

Author · Open source · 2024 - present

I was building Zenith's platform and the off-the-shelf AI tooling was causing more problems than it solved, so I built my own. lore is persistent memory that brings the right context to each task; forge runs the plan/build/review loop with purpose-built subagents; camp spins up a full dev environment for each feature across a set of related repos - backend, web app, and iOS simulator wired together - so I could run dozens at once. It's how I shipped it far faster than I could have otherwise - so I'm open-sourcing it now.

  • Claude Code
  • MCP
  • Python
  • git worktrees

Penny

Founding engineer · Zenith Health · 2024 - 2026

Penny is an AI evidence tool for women navigating pregnancy: you ask a question, it researches the literature and answers with a cited summary in plain language. Behind it: a streaming LLM pipeline on OpenAI models, a Phoenix/Elixir backend, a LiveView web app, AWS infrastructure, over-the-air mobile updates, and the observability under all of it. It ran in production for 16 months, answered 15,000+ questions for 5,200+ people, and grew monthly users about 15x in its first year.

  • Elixir
  • Phoenix LiveView
  • OpenAI
  • AWS CDK
  • PostHog

Expeditor

Release engineering technical lead · Chef Software · 2017 - 2021

Expeditor started as my own tool for getting Chef's software out the door without doing every release by hand. It became how the whole company shipped - a release engine that ran in every repo Chef owned, used by engineers and non-engineers to build, test, and ship the entire portfolio. It outlasted me and Chef's acquisition by Progress: the .expeditor directories still run automation across chef/chef, chef/automate, chef/inspec, and the rest.

  • Ruby
  • Buildkite
  • GitOps
  • Kubernetes

03Talks

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