Backend
- Java 8–21
- Spring Boot 3
- Spring Security
- Node.js
- NestJS
- REST APIs
- WebSockets · Redis
- SQL · MySQL · PostgreSQL · SQL Server
- MongoDB
Senior Product Engineer · Valencia
Facundo Costa Zini
Hands-on product engineer. I ship products, and I build companies.
01 — Bio
Hands-on engineer. Product owner. Founder.
Senior Product Engineer and founder, with more than 13 years building and operating production software. Core craft is backend and frontend together — Java, Spring Boot, Angular, React, TypeScript and Node.js — from customer discovery and architecture to the UI people actually use.
Healthcare, fintech, insurance, travel — among others. The through-line is picking up whatever the project is and shipping it. Iterpax is a part-time B2B SaaS for travel agencies: product discovery, architecture and hands-on development, outside regular working hours.
In Buenos Aires, ThinkUp Studios meant leading small teams and shipping client work across web and mobile. Owning the loop end to end, with Cursor and OpenAI every day to move faster and smarter.
Gamer: video games, escape rooms, board games, puzzles you crack with other people. That curiosity is why Carcassonne Scores and Keepout exist.
02 — Stack
The tools I use.
Frontend
- Angular
- React
- Next.js
- TypeScript
- Tailwind CSS
- Angular Material · PrimeNG
Architecture
- Software architecture
- B2B SaaS / multi-instance
- DDD / SOLID / Clean Architecture
- Docker · Kubernetes
- GitLab CI/CD · Jenkins
- Microservices
- OAuth 2.0 / OIDC / Keycloak
- AWS · DigitalOcean
Product
- Founding / product ownership
- Scrum / Agile leadership
- AI-assisted development
- Cursor · OpenAI
- Production support
03 — Experience
I adapt to what the work needs.
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Oct 2025 — now
Senior Full-Stack Developer Cegedim
Remote · Healthcare analytics
The challenge
A healthcare analytics platform that has to work across several medical products — not one dashboard, a system. Dashboards, a custom query builder, pivot tables, permissions and standalone deployments all collide. I took the async query path (WebSockets, background jobs, Redis), plus a Keycloak-secured audit platform and a dashboard to watch multiple BI instances.
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Apr 2023 — now
Founder & Product Engineer Iterpax Studios Part-time
Valencia, Spain · Independent B2B SaaS
The challenge
Travel operations still live in spreadsheets and chats. The bet was a modular B2B SaaS — reservations, operations, suppliers, itineraries, finance — on a multi-instance architecture. Client Manager replaced per-client deploys; provisioning went from days to hours. Built part-time, outside working hours.
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Dec 2024 — Oct 2025
Freelance Senior Full-Stack Developer Magnético
Remote · Three production projects
The challenge
Three production projects, architecture owned from client-server design through deploy. One was a commissions and employee platform. The nastier one was dropping React (Polotno) inside an Angular app without breaking lifecycle, communication or rendering.
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May 2025 — Sep 2025
Senior Java Developer UHS Contract
Remote, USA
The challenge
A million events a day, through a custom queueing system. Backend services in Java 17 and Spring Boot, SOLID and DDD. Kubernetes to keep the microservices reliable, and the load actually distributed.
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Apr 2021 — Apr 2024
Freelance Full-Stack Developer Willdom
Remote
The challenge
Two projects, two different goals. A health-insurance chatbot in Node.js, Angular and MongoDB. And Java 8 fintech systems that had to keep running in production.
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Sep 2017 — Apr 2021
Founder & Lead Developer ThinkUp Studios
Buenos Aires, Argentina
The challenge
One project at a time is boring — why not 15? I led two teams across 15+ client projects in Java, Spring Boot, Angular and Ionic, and built internal frameworks so a feature that took a day or two shipped in under an hour.
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Aug 2012 — Aug 2017
Full-Stack Developer & Software Architect Conexia
Buenos Aires, Argentina · Healthcare technology
The challenge
Healthcare management systems with a team of four. The architecture was fighting us. I redesigned the core around MVC and microservices so we could actually move under Scrum, instead of negotiating with the codebase every sprint.
04 — Projects
Companies I founded. Products I shipped.
Passion project
Iterpax
Modular B2B SaaS for inbound travel agencies: reservations, operations, suppliers, itineraries and finance. Multi-instance architecture, secure APIs, Java 17–21 / Spring Boot / Angular, MySQL and MongoDB. I founded it, and I keep building it part-time.
- Modular multi-instance architecture with secure APIs.
- Stack: Java 17–21, Spring Boot, Angular, MySQL, MongoDB, Docker.
- Client Manager: versioned deploys across isolated customer instances — onboarding from days to hours.
- Context-aware module that matches passenger groups to available tours.
Live
Carcassonne Scores
Mobile-first scorekeeper for Carcassonne, the well-known board game. A personal product I designed, built and deployed.
carcassonne.costazini.com.arWork in progress
Keepout
Angular game prototype — “How long can you keep them out?” Live demo on Firebase Hosting.
keepout-thinkup.web.appPrevious venture
ThinkUp Studios
Software studio I co-founded in Buenos Aires before Iterpax. Web, mobile, 15+ client projects.
thinkup.com.ar05 — Play
Gamer. Video games. Escape rooms. Board games.
I play. A lot. Video games, escape rooms, board games — anything that is a system you have to crack with other people. I like puzzles, rules, and the moment a messy problem clicks.
That is also why Carcassonne Scores and Keepout exist: products I build because I actually want to use them.
- Gamer
- Video games
- Escape rooms
- Board games