Java Developer - Java 21, Spring Boot, REST APIs and Microservices

Project overview

Job Overview

We are seeking an experienced and highly capable hands-on Java Developer to join our client's software development team.

The successful candidate will be responsible for designing, developing, testing, debugging, enhancing and maintaining robust, secure, scalable and high-performance Java applications and microservices.

This role requires recent commercial hands-on experience with Java 21 or later, strong practical expertise in Spring Boot, RESTful APIs, microservices, Test-Driven Development (TDD), SOLID principles, object-oriented programming and automated testing.

The ideal candidate must demonstrate proven experience personally writing production-quality Java code, developing business functionality, implementing APIs, creating automated tests, troubleshooting defects and delivering working software within an Agile environment.

This is a hands-on software development position, not a Cloud Architect or Solution Architect role. Candidates must be able to demonstrate their practical Java programming capabilities through technical interviews and coding assessments.

Key Responsibilities1. Java 21+ Software Development

Essential Skills and Experience

Candidates must demonstrate:

Desirable Skills and Experience

Candidate Profile

The ideal candidate will:

Important Role Clarification

This position is specifically for a hands-on Java Software Developer.

Candidates whose recent professional responsibilities are primarily focused on Cloud Architecture, Solution Architecture, Infrastructure Architecture or high-level technical design, without substantial recent Java coding experience, are unlikely to meet the role requirements.

Architecture and cloud experience are valuable supporting capabilities but cannot replace practical Java software development expertise.

Technical Assessment

Candidates must be prepared to demonstrate:

Demonstrable hands-on Java coding proficiency is mandatory.

• Design, develop, test, enhance and maintain enterprise-grade applications using Java 21 or later.
• Write clean, efficient, secure, maintainable and production-quality Java code.
• Develop Back End services, business logic and application components using Java and Spring Boot.
• Apply object-oriented programming, collections, streams, exception handling and modern Java features.
• Independently implement software features based on business requirements and technical specifications.
• Debug, troubleshoot, refactor and optimise Java applications.
• Participate actively in hands-on coding, pair programming and code reviews.
• Contribute to application design decisions while maintaining direct coding responsibilities.
• Test-Driven Development (TDD)
• Essential
• Apply TDD consistently as part of day-to-day software development.
• Follow the Red-Green-Refactor approach when implementing application functionality.
• Write automated unit tests using JUnit, Mockito and appropriate testing frameworks.
• Develop and maintain reliable automated test suites.
• Write testable code and ensure new functionality is supported by meaningful automated tests.
• Use automated testing to support refactoring, defect prevention and regression protection.
• Participate in code reviews to improve testability and software quality.
• SOLID Principles and Clean Code
• Apply SOLID principles in the design and implementation of Java applications.
• Follow object-oriented design, clean code practices and appropriate software design patterns.
• Use dependency injection, separation of concerns and reusable software components.
• Refactor existing code to improve maintainability, readability and testability.
• Identify and resolve code quality issues.
• Develop loosely coupled and maintainable application components.
• Spring Boot, REST APIs and Microservices
• Develop, implement and maintain RESTful APIs and microservices using Java and Spring Boot.
• Build controllers, service layers, repositories and Back End business logic.
• Implement API validation, exception handling, authentication and error responses.
• Develop integrations with internal and external systems.
• Work with HTTP, JSON, XML and API documentation standards such as OpenAPI/Swagger.
• Write unit, integration and API tests.
• Troubleshoot microservice communication and API integration issues.
• Develop and maintain SOAP web services where required.
• Database Development
• Develop database interactions using SQL, JDBC, JPA and Hibernate.
• Work with relational databases such as PostgreSQL, Oracle or MySQL.
• Write and optimise SQL queries.
• Implement appropriate transaction management and data access logic.
• Troubleshoot database-related application issues.
• CI/CD and Software Delivery
• Work with Git for source control and collaborative development.
• Use Maven or Gradle for build and dependency management.
• Contribute to CI/CD pipelines for automated building, testing and deployment.
• Integrate automated tests into software delivery pipelines.
• Work with Docker and containerised applications where required.
• Support application deployment, troubleshooting and maintenance.
• Agile Development and Collaboration
• Work within Agile/Scrum development teams.
• Participate in sprint planning, daily stand-ups, refinement, reviews and retrospectives.
• Collaborate with developers, testers, product owners, business analysts and technical leads.
• Participate in pair programming and peer code reviews.
• Translate user stories and business requirements into working software.
• Take responsibility for assigned development tasks and deliver high-quality solutions.
• Java 21+
• Mandatory: Recent hands-on commercial experience developing production Java applications using Java 21 or later.
• Hands-on coding
• Mandatory: Strong practical Java programming, debugging, testing and problem-solving capability.
• TDD
• Essential: Proven experience applying Test-Driven Development, including Red-Green-Refactor and automated unit testing.
• SOLID principles
• Essential: Strong practical understanding and application of SOLID, clean code and object-oriented design.
• Spring Boot: Hands-on experience developing Back End applications and services.
• RESTful APIs: Experience implementing, testing and maintaining APIs.
• Microservices: Practical experience developing and maintaining Java microservices.
• Automated testing: Experience using JUnit, Mockito and integration testing techniques.
• Databases: Experience with SQL and relational databases.
• Development tools: Experience with Git, Maven or Gradle and CI/CD practices.
• Agile: Experience working in collaborative Agile development teams.
• Pair programming: Willingness and ability to work in a pair programming environment.
• Behaviour-Driven Development (BDD) using Cucumber, Gherkin or similar tools.
• Spring Security, OAuth 2.0 and JWT.
• SOAP web services and XML.
• Docker and Kubernetes.
• AWS, Azure or other cloud environments.
• Kafka, RabbitMQ or other messaging technologies.
• SonarQube and static code analysis tools.
• Application monitoring, performance tuning and observability.
• Experience working in secure, regulated or government environments.
• SC or DV security clearance, where relevant.
• Be a genuine hands-on Java Developer with substantial recent production coding experience.
• Be capable of independently developing, debugging and testing Java application functionality.
• Demonstrate practical application of TDD and SOLID principles.
• Have experience developing Java applications, Spring Boot services and RESTful APIs.
• Be comfortable participating in pair programming and code reviews.
• Clearly explain their individual coding contributions to recent projects.
• Demonstrate strong analytical, debugging and problem-solving skills.
• Be confident completing practical Java coding assessments.
• Java 21+ programming and problem-solving.
• Practical Java coding, debugging and refactoring.
• TDD using JUnit and Mockito.
• Application of SOLID principles.
• Spring Boot and REST API implementation.
• Microservices development.
• Automated testing and code quality.

Project details

• Start: flexible
• Duration: 9 months
• Location: London M-25, United Kingdom, GB
• Rate: 56-63 EUR/h