Hey, I'm John Deliyiannis. I'm a software engineer based in Greece. I build web and mobile products from early idea to production.

I started out with hardware at university, then moved into web work while I was still a student. I began with WordPress, Joomla, HTML/CSS/JS and PHP in 2006, and moved into professional Rails work around 2010.

Most of my work has been in small teams where I had to own the full path from idea to production. I am comfortable across data modelling, backend, frontend, payments, infrastructure and deployment, but the real goal is making the product useful and stable.

Rails is my home base, but real product work is bigger than one framework. I use whatever gets the product shipped and keeps it maintainable.

Highlights of what I've built

  • Collaborate Healthcare: first engineer on a digital health platform for chronic-care workflows. I built and owned the stack, from data model to deployment, then helped grow the team to six. collaborate247.com
  • Lynx Educate: co-founded the engineering as Fractional CTO. I worked on access controls, audit logging and security policies that helped the platform through SOC 2.
  • DRAFA: a complete sports-venue booking product with a Rails API, React Native app, Redis-backed real-time scheduling and Stripe payments.
  • HTA-Hive: built RAG search and assistant flows over a large pharmaceutical document set across Rails, Angular and FastAPI.
  • Side projects I ship solo for fun: DCAloop, PressureTalks, DailyAcademia, HotelData and more.

What I work with

Rails and Hotwire are still the core. I also ship practical LLM and RAG features that run in production.

Ruby on Rails Hotwire React Native PostgreSQL AWS & Kamal Stripe FastAPI AI / LLMs / RAG

About this blog

I write about Ruby, Rails, product engineering, AI and automation. Most posts come from real problems I hit at work or in my own projects. I write the article I wish I'd found when I was stuck.

Find me on GitHub and LinkedIn, or email me at [email protected].