Senior engineer and technical lead for startups.
I'm John Aaron Nelson. For fifteen years I've built products and led the engineering behind them: growth experiments at Calendly, developer tooling at Pipedream, and first versions of products at a YC startup and as a fractional CTO. I do my best work on small teams where one engineer can move the product.
I also take on select consulting and project work: fractional CTO engagements, AI and MCP builds, and scoped projects with a clear finish line.
I'm also the person behind Atelier (elier.ai).
Highlights
Calendly, Growth. Shipped experiments that drove more than $1M in ACV in 2025, and led the push that doubled AI tool usage across engineering.
Pipedream, frontend lead. Led a team of five on the workflow builder of a developer automation platform; product adoption grew more than 30%.
Voiz Academy, fractional CTO. Took the company from Notion workflows to a production SaaS serving 1,000+ users, hired the engineering team, then hired my successor.
Batch.sh (YC W20), early engineer. Owned the product UX for a cloud infrastructure platform across web app, desktop app and website.
Areas of Expertise
Where I add the most to a team
How I work.
Straight answers.
I say what I think the right call is and why, including “we shouldn't build this.” Clear tradeoffs early save teams weeks later.
Boring tools, on purpose.
I reach for the well-understood option over the impressive one, and add complexity only when the problem demands it. Systems a team can reason about ship faster and break less.
Real people, even with AI.
AI is a force multiplier, not a replacement for taste, judgment, or responsibility. I write about the boundary between automation and accountable human work.
Hiring, or have a project?
Tell me about the role or the work. I reply within a couple of business days.