Java Developer - Hands-on - JAVA 21/25, TDD, Microservices - Inside IR35 - £500-550

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 Responsibilities

1. Java 21+ Software Development

• 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.

2. 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.

3. 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.

4. 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.

5. 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.

6. 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.

7. 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.

Essential Skills and Experience

Candidates must demonstrate:

• 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.…