Senior Kotlin / Java backend engineer in Barcelona, Spain.
I spent 6 years building and running an oncology patient-monitoring platform: a hybrid backend with heavy integrations with national and regional health systems, medical document exchange (HL7 CDA), and business-critical workflows. I like messy, legacy-heavy systems: I find the real constraints, fix what hurts most, and modernize step by step instead of risking a big rewrite.
- Led a Java → Kotlin migration that cut production bugs by ~20% and sped up the team
- Built APIs and integrations over REST, SOAP, Protobuf and XML/XSD, on PostgreSQL and OrientDB
- Built an LLM microservice for analyzing government contracts: batch inference, message-driven processing, containerized deployment
- Ship my own products end to end, from architecture to app-store release
- Eloqo — an AI speech coach for diction, fluency and vocabulary. Kotlin Multiplatform + Compose Multiplatform on Android and iOS, Firebase backend, on-device audio analysis (pace, WPM) plus AI feedback. Now in closed testing on Google Play.
- Addict — a pop-up dictionary for Linux in Rust + GTK 4. Select a word, press a hotkey, and see its meanings, synonyms and pronunciation, with the sense that fits the sentence. Offline dictionaries and OCR for text in images, plus optional DeepL. Ships as Flatpak and AppImage.
| Backend | Kotlin, Java, Spring Boot, Ktor, Exposed, Kafka |
| Integration | REST, SOAP, Protobuf, JSON, XML/XSD, HL7 CDA |
| Data | PostgreSQL, OrientDB, SQL |
| Mobile | Kotlin Multiplatform, Compose Multiplatform, Firebase |
| Systems | Rust, GTK 4, Linux, Flatpak |
| AI / LLM | Python, vLLM, local inference, agentic development with Claude Code |
| Delivery | Docker, GitHub Actions, Gradle, Maven |
I'm open to senior Kotlin / Java backend roles in Barcelona or remote across Europe, with English as the working language.