Joshua Onyema

engineer && developer

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Backend Services for Early Stage Products

Company

Brainstorm IT Solutions [Startup Agency]

Role

Java Backend Developer

Tools

Java, Spring Boot [MVC, Data JPA, Security], PostgreSQL, Hibernate, JWT, JUnit 5, Mockito, Git, Postman

Links

The Experience

Delivered Spring Boot backend services for multiple early stage products. I built REST APIs with validation and exception handling, kept endpoints consistent with clear API contracts, and focused on correctness so front end teams could integrate without surprises. I modelled relational data using Spring Data JPA and PostgreSQL, including relationships and transactional flows, and improved database performance using indexing and targeted SQL optimisation. I implemented authentication and authorisation using Spring Security and JWT, and added automated tests with JUnit 5 and Mockito to reduce regressions during ongoing feature work.