Full Stack Developer (Java, React, Next)

Sparta Global are hiring a Full-Stack Developer on a 12 Month Contract to build and improve web applications and API integrations supporting Data Fabric services.

The role combines a strong frontend focus using TypeScript, React and Next.js with integration work across Java and Spring Boot services. You will work closely with product, UX, backend and data teams to deliver accessible, secure and reliable features.

Key Responsibilities

• Develop and maintain responsive, accessible user interfaces using TypeScript, React and Next.js.
• Deliver end-to-end features across frontend components, state management and backend API integrations.
• Work with product and technical teams to define user journeys, data requirements and acceptance criteria.
• Build reusable components and maintain clean, well-structured code.
• Integrate with Java 21 and Spring Boot services, supporting changes to API contracts and data structures.
• Investigate and resolve issues across user interfaces, API integrations, performance and production reliability.
• Contribute to unit, integration and regression testing across frontend and backend services.
• Support monitoring, logging and performance improvements for the features you deliver.
• Participate in technical design, code reviews and deployment preparation, maintaining secure coding standards.

Required Skills & Experience

• Strong experience developing web applications using TypeScript, React and Next.js.
• Good understanding of frontend architecture, including component design, state management, routing and accessibility.
• Experience delivering or supporting full-stack features across frontend applications and backend services.
• Working knowledge of Java and Spring Boot, with the ability to contribute to backend integration work.
• Experience working with REST APIs, data transfer objects, authentication flows and integration contracts.
• Understanding of secure development practices, including token handling, role-based access and safe data handling.
• Ability to write maintainable code and contribute to technical design discussions and code reviews.
• Strong problem-solving skills, including investigating production issues across UI and API layers.
• Good communication skills, with the ability to explain technical trade-offs to technical and non-technical stakeholders.

Desirable Experience

• React Query, TanStack Query, Redux Toolkit or similar tools for state management and data fetching.
• Axios, form handling, validation and UI component libraries.
• Spring Web, Spring Security or Spring Data JPA.
• PostgreSQL, database design or database migrations.
• OpenTelemetry, Micrometer, structured logging or production monitoring tools.
• Cloud-native or containerised delivery environments.
• Automated testing using JUnit 5, Vitest, Playwright or equivalent frameworks.