Open to backend & data roles · Brussels, BE

Harold
Rajaonarison Backend · Data Engineering · Data Science

Building scalable data pipelines and high-throughput backend systems in Java & Python. Fluent in event streaming, microservices, and the entire data lifecycle — from ingestion to insight.

// sample pipeline running
📡 Kafka topic ingestion source
⚙️ Spring Boot processor transform
🗄️ PostgreSQL / MinIO sink store
📊 Analytics & dashboards serve
🤖 ML model inference predict
2+
Yrs experience
3
Projects shipped
5+
Tools mastered
GB data processed
Java 17+ Apache Kafka Python Spring Boot PostgreSQL Docker Pandas / NumPy Scikit-learn REST API ETL Pipelines MinIO GitHub Actions Hexagonal Arch Java 17+ Apache Kafka Python Spring Boot PostgreSQL Docker Pandas / NumPy Scikit-learn REST API ETL Pipelines MinIO GitHub Actions Hexagonal Arch
Technical stack

What I build with

Backend Core
Java 17+ / Spring Boot Hexagonal Architecture REST APIs / OAuth2 MapStruct / JUnit Maven / Gradle
🌊
Data Engineering
Apache Kafka ETL Pipelines PostgreSQL / MinIO Docker / GitHub Actions Event-driven systems
🐍
Data Science
Python · Pandas · NumPy Scikit-learn (basics) Data visualisation Statistical analysis Chart.js / Matplotlib
🏗️
Infra & DevOps
Docker / Compose CI/CD · GitHub Actions Object storage (MinIO) Microservices patterns Security scanning
Selected work

Projects & pipelines

// 01
🛒
Order & Pay

Event-driven microservices ordering platform. Kafka handles inter-service messaging; GitHub Actions automates builds and an AI-powered PR review bot keeps code quality high.

Kafka Spring Boot Docker GH Actions Hexagonal
In progress
// 02
🗄️
HostIt

Self-hosted object storage service built on MinIO. Exposes clean REST endpoints for upload/download workflows with JWT auth middleware and structured audit logging.

MinIO Spring Boot Docker REST API JWT
In progress
// 03
Plannergy

AI-powered energy analytics dashboard for industrial manufacturers. Aggregates sensor data, applies predictive models, and visualises consumption trends for Luminus stakeholders.

Data Analytics AI/ML Chart.js Tailwind
Pitched
// 04
📦
Data pipeline project

End-to-end batch + streaming pipeline — ingestion, transformation, storage, and analytical layer. Coming soon.

Python Kafka ETL
Planned
+
Your next project here
Background

The engineer
behind the data

I'm a junior backend & data engineer based in Brussels. My core stack is Java 17+ with Spring Boot, shaped by a six-month internship at FPS Finance where I built production microservices using hexagonal architecture.

On the data side, I work with Apache Kafka for event streaming, design ETL pipelines, and apply Python for analytics and basic ML modelling. I'm currently sharpening those skills through the Java@FIN program at Switchfully / Egov Select.

Beyond the terminal, I've pitched an AI analytics product to Luminus, explored geopolitical data modelling, and built karaoke tools — proof that curiosity drives better engineering.

Backend Intern — Microservices 2024
FPS Finance · Brussels Java · Spring Boot · Hexagonal
Java@FIN Developer Program 2025 →
Switchfully / Egov Select Backend · Architecture · CI/CD
Data Product — Plannergy 2024
Luminus Startup Initiative AI Analytics · Energy Data
M.Sc. Information Systems 2023
École-IT Brussels Architecture · Systems Design
B.Sc. Electronics & Computer Systems 2021
ISPM Madagascar Foundations · Hardware · Code
Contact

Let's buildsomething.

Open to backend engineering, data engineering, and data-adjacent roles. Also happy to talk pipelines, architecture, or just grab a virtual coffee.