Competence
Java is the language I've shipped production code in since 2017, across two banks, a payments group and an insurance platform. Today that means Java 21 and Spring Boot 3.5.
In short
Yassir Halaoui is a senior Java developer working with Java 8 through 21 and Spring Boot up to 3.5, including Spring Batch, Spring Data JPA, Spring AOP and Hibernate. He has built Java services from scratch in banking and payments, migrated batch jobs onto Spring Boot, and designed idempotent asynchronous processing for payment card workflows.
Pluxee · 2025 to now
Built a Java 21 and Spring Boot 3.5 service from scratch that secures PIN retrieval between a card processor and a mobile app, with idempotent, webhook-driven processing and a reusable audit trail built on Spring AOP.
Docaposte · 2024 to 2025
Designed and built features of an electronic record exchanged between insurers, on Spring Boot 3 and Java 21, and handled its production incidents and performance work.
Société Générale · 2022 to 2024
As lead developer, built a centralized fee-declaration platform for a public administration from scratch on Java 11, Spring Boot and Spring Batch, and brought two junior developers up to speed.
Consulting · 2022
Migrated legacy batch processing to Spring Boot for an automotive rental platform, and replaced hand-written JDBC with Spring Data JPA.
CIH Bank · 2017 to 2022
Built the batch that executes standing-order transfers automatically, and an ATM cash-deposit API in Spring Boot behind a secured API gateway.
I've worked on every long-term-support version from 8 to 21, which mostly means I've done the upgrades. The hard part of a Java migration is rarely the language. It's the libraries that moved from javax to jakarta, the JAXB that left the JDK, and the batch job nobody has run on a laptop in years.
Not everything is a stream. Month-end processing, file ingestion and reconciliation have a start, an end and a question someone asks the next morning: did it finish? Spring Batch answers that with restartable chunks and run identity, and I'd rather use it than rebuild it on top of Kafka.
The bugs that hurt in payment systems live in transactions, unique constraints and concurrency, and a mocked repository can't see any of them. My integration tests run against a real PostgreSQL in Testcontainers, including one that fires the same message from eight threads at once.
For missions in Paris and Île-de-France, on-site or remote across France. Send the dates and the stack and I'll answer the same day.
Yes. I've worked on every LTS from 8 to 21. A migration plan starts with the dependencies that changed namespace or left the JDK, because that's where the breakage hides, then moves module by module behind the existing tests.
Spring Batch when the work is bounded, restartable and reconciled against a source of truth. Kafka when it's unbounded and latency matters. Most real systems use both, with a clear boundary between per-run and per-message guarantees.
Always. Unit tests for logic, and integration tests against a real database in Testcontainers for anything touching transactions, constraints or concurrency.
Field note · Event-driven Java
Idempotency keys are not enough when money movesField note · Secure integration
WS-Security in 2026: making a 2004 spec work with Java 21Case study · B2C
RevealTogetherCompetence
Kafka & event-drivenCompetence
API security & integrationCompetence
PostgreSQL & dataHire for this
Java & React in Paris