I build products and the teams behind them.
I'm John Gregoriadis. I've helped launch the Xero App Store, Cotiss and Prosaic, led engineering teams, and built and sold a startup.
Principal Engineer at Prosaic ↗. Previously Head of Engineering at Xero and Cotiss.
Experience
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Prosaic
2025–presentPrincipal Engineer
Helped launch an AI-native accounting product. I work in a small team across authentication, core APIs, Model Context Protocol (MCP) integration and agentic workflows, connecting the product experience to the architecture underneath.
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Cotiss
2022–2025Head of Engineering
Recruited the engineering team, set the technical strategy and helped launch the procurement product. Worked across product, design and engineering to deliver the MVP and build the team's ability to keep shipping.
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Xero
2018–2022Development Team Lead → Development Manager → Head of Engineering
Helped launch the Xero App Store and led engineering for the API and ecosystem teams. Built teams that shipped multiple times a day, with a focus on ownership, continuous delivery and developing engineering leaders.
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Vend
2012–2018Support Engineer → Engineer → Lead Engineer
Progressed from customer support into engineering leadership, managing three teams across billing platforms, integrations and third-party payments. Starting in support still shapes how I work: understand the customer's problem, then follow it through the system.
Founder experience
Shopim
Founder · Acquired by Vend
Founded and built a chatbot product for retail and eCommerce. Taking a product from an idea through to acquisition gave me a practical understanding of both the engineering and commercial decisions behind a company.
Spotrisk
Co-founder
Co-founded an eCommerce fulfilment-risk platform and built a team of five. Worked across product, engineering and pre-seed fundraising, including pitches and investor conversations.
How I work
- Start with the product.
- I work with product and design to understand the customer's problem, choose the first useful version and connect the technical plan to a commercial goal.
- Stay close to the engineering.
- I still write code and test ideas myself. That helps me make the tradeoffs around architecture, reliability, security and delivery concrete enough for a team to act on.
- Give people room to own the work.
- Clear context, honest feedback and responsibility matter. I invest in hiring and development so the people closest to a problem can make good decisions and take on greater responsibility.
How I think
- Engineering I Spent 29 Hours Debugging iptables to Boot VMs in 4 Seconds Building the root filesystem, fixing UFW forwarding and cleaning up guest processes.
- Product & founders The product market fit gauntlet Hiring for uncertainty, revising the roadmap and keeping the product easy to change.
- Leadership The dent and the crater How setbacks change the way you lead, and what your team learns from your response.
Say hello
I'm always happy to talk about building products, technical leadership and growing engineering teams.
Outside software, I'm a dad on Auckland's North Shore. I volunteer as a Civil Defence First Responder and enjoy boxing.