Diamantis Kyriakakis

Hands-on CTO and principal architect with 20+ years building and operating high consequence backend platforms across telecom, messaging, payments, and SaaS. I lead from product shape through architecture, implementation, and incident response, and I stay close to production the whole way.

For over a decade I was CTO and Lead Architect at a telecom messaging company, where I owned the technical platform end to end and built the hard parts myself. A few outcomes: I brought core signaling infrastructure fully in house for a 9x profitability improvement, rebuilt the core routing engine for 3x throughput at lower memory usage via zero downtime migration, and cut customer complaints by around 70% with ML and LLM assisted operational automation. More recently I worked with a licensed payment institution on regulated payment flows and reporting under real compliance constraints.

I am a polyglot engineer, equally productive across Java and Spring, Rust, Node.js and TypeScript, Python, and C#/.NET, with React, Next.js and Vue on the front end. I work daily with PostgreSQL, Redis, distributed messaging and queues, Docker, Kubernetes, and AWS. Lately I have been building applied AI infrastructure, agent and tool platforms and RAG systems, for production rather than demos.

What I am best at is owning the whole problem: choosing what to build, designing the system, writing the critical parts, shipping it safely, and operating it under load. I care about correctness, failure modes, and production reality more than clean diagrams.

Open to senior, principal, and staff backend and platform roles, hands on architect roles, and contract or fractional engagements. Remote across the EU (based in Patras, Greece, EET), set up for full remote collaboration. I work B2B through my own LLC.