Belfast, NI · Open to UK & remote

// Γιάννης Καρασαββαΐδης Ioannis
Karasavvaidis.

Principal Software Engineer / Tech Lead

I build enterprise SaaS end-to-end — backend, frontend, data, cloud and security — and I've been doing it for 22+ years. Two-time founding engineer at Puppet (now Perforce), where I built an AI-native engineering practice and led a team of 18. Now I'm looking for what's next. Greek by origin, Belfast by postcode, terminal by default.

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Ioannis Karasavvaidis
22+ years shipping
2×
Founding engineer at Puppet — POC to GA-ready, K8s-deployed SaaS
5→18
Grew & tech-led the engineering org; mentored grad → Principal
5×
Hyperscalers ingested — AWS, GCP, Azure, OCI, IBM Cloud
20s→
p95 query latency taken to sub-second over billions of rows
15+
Years a Greek e-commerce platform has run in production
Selected work

Products I took from a blank repo to production.

A few things I'm proud of — what they do, and the hard parts I owned.

01

Puppet Early Access

End-to-end owner · LLD authorMulti-cloud FinOps platform2022 → 2026

Ingests cloud billing across five hyperscalers, normalises it through the FOCUS specification, surfaces spend analytics & optimisation recommendations, then auto-generates Terraform pull requests so customers apply savings through GitOps.

  • Multi-tenant by design — database-per-tenant in ClickHouse, schema-per-tenant in PostgreSQL, async Kafka messaging, token-auth REST for S2S. SOC 2-ready from day one.
  • Ingest at scale — terabytes/day, dual-trigger (scheduled + SQS event-driven), KEDA scaling the parser fleet 0→N on backlog with backpressure, DLQ & retry. Zero production data-loss.
  • Sub-second analytics — ClickHouse materialised views + pre-aggregation + Redis caching + query rewriting, responsive over billions of rows.
  • GraphQL platform — Apollo Federation supergraph over ~7 Go subgraphs, codegen typings into a React + TanStack UI; reactive state over Redis pub/sub + WebSockets.
GoClickHouseKafkaKEDAGraphQL FederationReactTerraformKubernetes
02

The AI-native SDLC

Owner & org-wide enablementAgent-driven engineering2024 → 2026

I built the full agentic pipeline my team ships through — ticket → low-level design → epic/spec → plan → review → PR → code review → CI → merge → follow-up — and rolled it out across an 18-engineer org.

  • Authored the project CLAUDE.md, project-specific Claude skills, and custom MCP servers integrating internal tooling.
  • 55 tickets to staging in 24 hours on a recent freelance project via a 99% agentic workflow — the proof point.
  • Ran hands-on enablement & training across the org, plus AI-augmented onboarding for new hires.
Claude CodeMCP authoringAgentic SDLCAgent code review
03

Puppet Comply

Founding architect · UI Tech LeadCompliance SaaS2020 → 2022

Took the compliance product from POC to GA-ready Kubernetes deployment — establishing the deployment platform, CI/CD and full-stack testing infrastructure from scratch.

  • As UI Tech Lead: a TypeScript + React component library, state-management and API patterns, frontend CI/CD, error tracking and FE coding standards.
TypeScriptReactKubernetesCI/CDTesting infra
04

Studio110 — efantasy.gr

Founder & Principal EngineerGreek e-commerce platform2009 → present

Founding engineer and 15+ year maintainer of a Greek e-commerce platform: 50,000+ SKUs across 37 categories, shipping to 70 countries. I designed the high-availability cluster and the ERP-to-storefront integration bridge from scratch — ERP as source of truth, real-time sync to multiple storefronts.

  • Cross-domain delivery: payment gateways, ERP integration, custom CMS, streaming media (web radio/TV, mobile broadcasting), VPS/cloud infra, LAN/WAN security.
  • Built & supported distributed dev teams — interviewing, mentoring, code review, engineering standards.
High availabilityERP integrationPaymentsPHPCustom CMSStreaming
Career

22 years, condensed.

From set-top-box UIs on constrained hardware to Principal & Tech Lead on multi-cloud SaaS.

Oct 2017 — May 2026

Puppet (acquired by Perforce, 2022)

Belfast, UK
  • Principal Software Engineer II / Tech Lead — Perforce · Aug 2022 → May 2026
  • Principal Software Engineer / Tech Lead — Puppet · Apr 2021 → Aug 2022
  • Senior Software Engineer / UI Tech Lead · Jan 2020 → Apr 2021
  • Senior Software Engineer · Oct 2017 → Dec 2019

Founding engineer on two products (Comply, Early Access). End-to-end owner of the FOCUS cost-data service and React UI; LLD author for 10+ Go/Python microservices. Built the team from 5 to 18 with decision authority on every hire.

Feb 2009 — Present

Studio110 — Founder & Principal Engineer

Belfast / Thessaloniki · Remote · in parallel

Independent product engineering. 15+ year maintainer of efantasy.gr; high-availability clusters, ERP integration bridges, payments, custom CMS and streaming media for clients across Greece & the UK.

Jan — Oct 2017

IBM — Frontend Developer

Belfast

Architected and maintained QRadar security applications. Designed CI/CD with GitLab CI, automated dev-env setup via Docker & Bash, delivered secrets encryption, modular proxy systems and application isolation; built unit/E2E/validation testing infrastructure.

Jun 2016 — Jan 2017

RepKnight — Frontend Engineer

Belfast

Led modernisation of a legacy PHP application into a real-time React platform. Built real-time data-visualisation dashboards over WebSockets with a custom Node.js bidirectional bridge server; ran the end-to-end migration with no downtime.

2000 — 2016

Earlier — Greece & Belfast

ARRIS / Pace · UpMate · Radiothessaloniki · Net Fans

Set-top-box UI on resource-constrained devices & performance optimisation (ARRIS / Pace). Architected the Easy Admin CMS & Dynamic Action Suite flagship PHP CMS, initial build of efantasy.gr, ERP integrations & multi-store management (UpMate). Full-stack web, DB & server operations across radio and gaming-server businesses.

Toolbox

Deep across the stack — not a specialist who forgot the rest.

Languages

GoTypeScriptJavaScriptPythonRubyPHPSQLBash

Frontend

ReactApollo ClientTanStack Router / QueryTailwind CSSViteWebpackSCSS

Backend & APIs

Go microservicesGraphQL (Apollo Federation)gqlgenRESTgRPCWebSocketsEvent-drivenS2S authIdempotency

Data & Streaming

ClickHousePostgreSQLRedisApache KafkaAWS SQSMaterialised viewsReplacingMergeTree

Cloud & Infrastructure

AWSGCPAzureOCIIBM CloudKubernetesKEDADockerHelmTerraformArgoCDGitLab CIGitHub Actions

Observability

PrometheusGrafanaOpenTelemetryAlertmanagerELK StackOpenSearch

AI / Agentic Engineering

Claude CodeMCP server authoringAgentic SDLCProject Claude skillsAgent code reviewAI onboarding

Architecture

Multi-tenant SaaSMulti-cloudFinOpsFOCUS specGitOpsEvent-drivenSOC 2-readyRBACOIDC / OAuth2BYOC

Leadership

Technical directionLLD authorshipHiring through PrincipalMentorshipCross-team interviewingFeature-team leadership
Open source & public work

Things I build because I want to, not because a ticket said so.

codex-mcp-server

An MCP server that exposes the OpenAI Codex CLI to any AI client (e.g. Claude Code), enabling agent-to-agent collaboration.

MCP · Go
second-brain-mcp

A personal knowledge MCP server — your notes, surfaced to your agents.

MCP · Knowledge
GraphQLens

A browser extension to mock GraphQL queries — build the frontend before the backend exists.

Browser extension
Conventional Comments

A browser extension for PR reviewers — structured feedback in the conventional-comments format.

Browser extension
Neovim plugins & Actions

Authored and contributed plugins for Neovim and reusable GitHub Actions across multiple projects.

Neovim · CI
Personal sites

strongpasswordmeter.com & netfans.gr — small useful tools and projects that have lived online for years.

Live · netfans.gr
About

I'm a builder who never stopped being curious — happiest with a terminal open, a hard problem on the whiteboard, and a team I can level up around me.

Born and raised in Thessaloniki, based in Belfast for years now — so a lot of my work quietly bridges two places. I've spent 22+ years going deep across the whole stack: I'll happily argue ClickHouse query plans in the morning and pixel-tune a React component in the afternoon. Lately I'm all-in on AI-native engineering — authoring MCP servers and building agentic workflows that make whole teams faster, not just me.

I care most about the human side of this craft: hiring well, mentoring people from graduate to Principal, and leaving codebases and engineers better than I found them. Outside the editor, I'm a tinkerer at heart — open source is my idea of a relaxing evening.

Contact

Let's build something solid.

Hiring, collaborating, or just want to talk shop about ClickHouse or agentic SDLCs? My inbox is open.

the@greekdev.io↗ linkedin.com/in/johnkarasavvaidis↗ github.com/CoMfUcIoS↗

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