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Open to opportunities
Ioannis Krokos
Full-stack product engineer
Zurich 🇨🇭
Mykonos 🇬🇷
I build and operate production software — from a hospitality SaaS running in 9 hotels to 500+ client websites — backed by 12+ years of experience.
Working with React, Next.js, TypeScript, and Node.js — backed by PostgreSQL, Supabase, and MongoDB in production.
- Zurich 🇨🇭
- Mykonos 🇬🇷
- hotels running GuestSync
- 9
- client websites delivered
- 500+
- years of experience
- 12+
01 — Featured Work
GuestSync
A multi-tenant hospitality SaaS I designed, built and run on my own. Nine hotels in Mykonos run their daily guest operations on it, all from one deployment.
What I own
- Architecture, schema and API
- Deployments on Railway
- Observability with OpenTelemetry and Grafana Cloud
- Client onboarding and support
Next.jsTypeScriptSupabaseRailwayOpenTelemetryGrafana Cloud
Service level objectives6 alert rules
| Guest portal availability | 99.9% |
|---|---|
| Guest portal latency | p95 < 500ms99% of the time |
| Admin API latency | p95 < 500ms99% of the time |
| Per-tenant error rate | 99.5% |
02 — Writing
Latest writing
Notes on building and running production software.
- 12 September 20266 min read
Adding Observability to a SaaS Running 9 Hotels
GuestSync ran for years on deploy logs and phone calls from hotels. This is how I gave it OpenTelemetry, four SLOs and burn rate alerts without a big vendor, and what it found first.
- 8 September 20268 min read
Where Automation Should Stop
I built an AI agent that runs almost my entire invoicing workflow. It is deliberately incapable of issuing an invoice. This is why.
- 16 November 20254 min read
Celebrating Community: ZurichJS 1st Anniversary Meetup
Reflecting on a year of ZurichJS and why developer communities matter for knowledge exchange, ecosystem understanding, and professional growth.
03 — About
About me
I'm Ioannis Krokos, a full-stack product engineer. I design, build, and operate GuestSync, a multi-tenant hospitality SaaS running daily guest operations across 9 hotels in Mykonos, with production observability (SLOs, tracing, alerting) built in. I own it end-to-end, from architecture to client onboarding and support. Since 2015 at Webee Web Agency, I've also delivered 500+ responsive websites and modern applications, translating complex business requirements into robust technical solutions with React, Next.js, and TypeScript.
- Location
- Between Zurich 🇨🇭 and Mykonos 🇬🇷 · EU citizen · Open to relocation
- Languages
- Greek (native) · English (fluent) · German (actively learning)
- Community
- ZurichJS
04 — Stack
Skills & tech stack
What I build, ship and run software with.
- Frontend
- React, Next.js, TypeScript, Tailwind CSS
- Backend
- Node.js, Express
- Database
- PostgreSQL, Supabase, MongoDB
- Deployment & Cloud
- Vercel, Railway, Cloudflare Workers, AWS
- Observability
- OpenTelemetry, Grafana Cloud, SLOs & Error Budgets, Distributed Tracing
- AI Tooling
- Anthropic Claude, Cursor, Workers AI
TypeScript-first. React and Next.js in production, shipped weekly.
05 — Experience
Experience & resume
12+ years of building digital solutions, collaborating with teams, and delivering results.
2015 — Present
Co-Founder & Lead Developer
Webee
Co-founded and lead development at Webee, a web agency serving the Mykonos hospitality sector.
- 500+ production websites, booking systems, and payment integrations built with Next.js, React, and PostgreSQL.
- Designed and built GuestSync solo: a multi-tenant hospitality SaaS (Next.js, Node.js, PostgreSQL) in production across 9 hotels.
- Own GuestSync end-to-end, from schema and API to deployments and observability.
- Instrumented it with OpenTelemetry and Grafana Cloud: four SLOs, burn rate alerting, and traces that carry no guest PII.
2013 — 2015
Frontend Web Developer
P.aR Publishing
Developed responsive interfaces for 10+ client projects using HTML, CSS, and JavaScript. Contributed to CMS solutions and agile workflows.
2016 — 2019
Bachelor's Degree, Computing
University of East London
Focused on software development, gaining foundational knowledge in programming, databases, and IT systems.
06 — Contact
Looking for a full-stack product engineer for your team?
I'm open to full-time roles and freelance projects. Let's talk about how I can help your team ship great products.