Experience

MaibornWolff · Client work

Customer portal modernization

Upgrading a Spring Boot microservice estate without big-bang releases.

Details anonymised · figures describe my own work

Overview

An Azure-based microservices portal where an enterprise's customers manage their accounts and invoices online. I worked as a backend engineer in a feature team shipping customer-facing capabilities.

The problem

The portal ran on many Spring Boot services that had to move to newer framework and Java versions while staying in production, with legacy behaviour that existing tests did not fully cover.

The approach

Incremental refactoring, one service at a time, backed by structured unit-testing patterns and quality gates in code review. Reusable GitLab CI templates made releases repeatable, and clearer API contracts across REST and GraphQL integrations cut down rework between teams.

Highlights

  1. Moved 10+ Spring Boot services from 2.7 to 3.3 and onto Java 21, one service at a time
  2. Introduced structured unit-testing patterns and quality gates in reviews
  3. Standardized CI/CD with reusable GitLab CI templates
  4. Shipped multi-service features across REST and GraphQL integrations
  5. Mentored junior engineers on clean code and delivery practices