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JUSTEVERYWHEREFLOW. BUILD. SCALE.
Software developmentRole ID: 43170

Senior Java Developer

We are looking for a senior Java developer to join an existing project where key backend parts of the system need to be stabilised, refactored, and further developed.

This is not a greenfield project. The system is already live, but it includes technical debt and areas that need to be reworked so that it becomes more stable, easier to maintain, and ready for further development.

What you'll be doing

You will be part of a senior engineering team taking ownership of important parts of an existing system. The main goal is to get oriented in the codebase quickly, understand the current architecture, identify weak points, and gradually deliver technical improvements.

Your responsibilities will mainly include:

  • backend development in Java 21 and Spring Boot,
  • analysis and refactoring of the existing codebase,
  • reducing technical debt,
  • designing a more stable and maintainable architecture,
  • working with MongoDB, Redis, and RabbitMQ,
  • optimising system performance and stability,
  • writing and maintaining automated tests,
  • code reviews and improving engineering quality,
  • active participation in agile delivery, sprints, and stand-ups,
  • using AI tools for development, analysis, review, and testing.

Tech stack

Backend

  • Java 21
  • Spring Boot 3.4.1
  • MongoDB
  • Mongock
  • Redis / Redisson
  • RabbitMQ

Testing

  • automated backend testing as a standard part of development,
  • unit and integration tests for Java / Spring Boot applications,
  • experience with JUnit 5, Mockito, Spring Boot Test, and Testcontainers,
  • testing REST APIs, business logic, the persistence layer, and integration scenarios,
  • verifying integrations with MongoDB, Redis, RabbitMQ, and external services,
  • using mocks, stubs, and isolated test environments,
  • tests as a safety net during refactoring, architectural changes, and technical debt reduction,
  • integrating tests into the CI/CD pipeline.

DevOps exposure

  • GitLab CI
  • Docker
  • Kubernetes

What we expect

We are looking for a senior developer with experience building production systems who can start bringing value quickly even in an existing project.

You should have:

  • a very strong command of Java and Spring Boot,
  • experience designing and evolving backend services,
  • the ability to quickly navigate an unfamiliar codebase,
  • experience with technical debt, refactoring, and system stabilisation,
  • hands-on experience with databases, ideally MongoDB,
  • knowledge of integration technologies such as RabbitMQ, Redis, and similar tools,
  • the ability to write and maintain automated tests,
  • experience with code reviews,
  • experience working in agile teams,
  • the ability to think independently, propose solutions, and drive them through to production.

Experience with AI-driven development is a major advantage, for example with Claude Code, GitHub Copilot, Cursor, or similar tools. We are not looking for a classic ticket developer, but for someone who can use AI to speed up analysis, solution design, review, testing, and implementation itself.

Who we're looking for

We are looking for a senior Java developer who is comfortable working with an existing system, technical debt, and a more complex environment. What matters most is the ability to quickly understand the current state, propose a meaningful solution, and deliver high-quality output.

The project is a good fit for experienced contractors, software studios, or smaller teams that can start quickly and deliver high-quality work in a more demanding environment.