Personal details

Željko H. - Remote full-stack developer

Željko H.

Based in: 🇭🇷 Croatia
Timezone: Zagreb (UTC+1)

About

Senior Systems Engineer | .NET & Event-Sourcing Specialist (AI-Native)

High-velocity engineer with 14 years of experience specializing in rebuilding legacy monoliths into scalable, event-driven architectures using the Strangler Fig pattern. Expert in .NET/C#, Postgres, and NodeJS, with a focus on "Audit-by-Default" systems for highly regulated industries (HealthTech, Fintech). AI-Native workflow practitioner utilizing Claude Code and Codex to drive rapid domain modeling and production-grade delivery. Proven track record in complex scheduling, multi-tenant isolation, and clinical compliance.

Work Experience

Senior Software Engineer
Pdftools | Jun 2025 - Aug 2026
C#
PostgreSQL
Google Analytics
TypeScript
React
HubSpot
.NET
Next.js
AWS
  1. Architected and built a containerized, self-hosted human-in-the-loop web app enabling enterprise customers to review and confirm AI-detected sensitive data in PDFs before redaction is finalized, deployable inside customers' own networks.
  2. Built a full-stack demo playground for the SDK tools — backend and frontend — allowing users to test and try out the products interactively.
  3. Managed the internal admin portal for license management, giving sta control over customer licenses and entitlements.
  4. Maintained the customer-facing portal where customers manage their own licenses.
  5. Owned the full public website end to end.
Full-Stack Developer
TheBase | May 2023 - Dec 2024
Stripe
React
ArangoDB
Kotlin
HubSpot
AWS
  • Engineered a high-concurrency Scheduling & Matching engine using Kotlin/Ktor, handling complex constraint-solving for real-time task assignment across multiple properties.
  • Integrated Apaleo and Stripe via typed contracts and gateways, ensuring financial auditability and reliable payment reconciliation.
  • Reduced operational errors by 25% through the implementation of a projections-based dashboard, providing real-time visibility into distributed system states.
  • Kotlin, Ktor, Kotlin/JS, Preact, ArangoDB, AWS, Stripe, Apaleo, Hubspot, WeWash

Projects

TheBase Co-Living
Stripe
React
ArangoDB
Kotlin
HubSpot
AWS
The Base develops and operates shared living spaces aimed at fostering social connections and addressing urban loneliness. - Served as a Full-Stack Developer, focusing primarily on backend development to build scalable, efficient, and robust systems. - Designed and implemented a complex housekeeping solution that optimized scheduling, task assignment, and progress tracking, increasing housekeeping efficiency by 40% and reducing errors by 25%. - Developed a back-office Property Management System (PMS) that streamlined administrative tasks, improving staff productivity by 40% and reducing manual workload by 30%.
Alpakas
2022
PostgreSQL
PayPal
Google Analytics
Firebase
Stripe
React
Circleci
React Native
Sentry
NestJS
AWS
Alpakas is an innovative online grocery platform committed to a zero-waste approach. It offers a curated selection of sustainably sourced products designed to minimize packaging waste and promote environmental responsibility. - Architected and built the entire backend system ensuring scalability, reliability, and maintainability to support rapid growth and high user demand. - Developed an intuitive admin dashboard, simplifying product and warehouse management, reducing administrative workload by 35%, and improving inventory accuracy by 20%. - Contributed to the development of the mobile app and frontend web app, creating seamless, user-friendly interfaces and ensuring consistent functionality across platforms. - Engineered a seamless e-commerce platform, integrating multiple payment gateways and order tracking, enhancing customer satisfaction while streamlining staff operations for efficient management.

Education

Sveučilište Josipa Jurja Strossmayera, Elektrotehnički fakultet Osijek
Master's degree・Computer Engineering - Process Computing
Sep 2008 - Jun 2014