Full Stack Engineer

Job Title: Senior Full Stack Software Engineer – Real-Time Systems & UX/UI

Location: Worcestershire (Hybrid)

Employment Type: Fixed Term Contract, INSIDE IR35

Duration: 9 months to 1 year

Note: Visa Sponsorship is not available for this role

About the Role

We are looking for an experienced Senior Full Stack Software Engineer – Real-Time Systems & UX/UI to support the modernisation and enhancement of an established SaaS software platform.

This is a hands-on engineering role suited to someone with a strong software development background who has worked with complex backend systems, asynchronous architectures, real-time communications and data-intensive applications, and who also understands how to translate complex technical functionality into intuitive and effective user interfaces.

The immediate priority will be to understand the existing platform, simplify and refactor areas of technical complexity, improve maintainability and strengthen the underlying architecture. You will then play a key role in modernising the front-end experience, improving workflows and developing a cleaner, more intuitive and visually modern GUI.

The successful candidate should be capable of working across the full technology stack and taking ownership of solutions end-to-end, with minimal reliance on additional development resources.

Key Responsibilities

• Analyse and understand an existing complex SaaS application and its underlying architecture.
• Identify technical debt, unnecessary complexity and opportunities to simplify the existing codebase.
• Refactor and modernise legacy or heavily customised application components.
• Design and develop scalable, maintainable backend services and application functionality.
• Work with asynchronous and event-driven architectures.
• Develop and maintain systems supporting real-time communications and data processing.
• Work with APIs, messaging technologies and communication protocols used within real-time applications.
• Design, optimise and integrate relational and time-series databases.
• Troubleshoot complex application, integration, performance and data issues.
• Improve application performance, scalability, reliability and maintainability.
• Develop and enhance front-end functionality and user interfaces.
• Translate user and business requirements into practical technical and UX/UI solutions.
• Simplify complex technical workflows into intuitive user experiences.
• Produce or contribute to wireframes, prototypes and interface concepts where required.
• Develop reusable UX/UI components and maintain consistency across the application.
• Work closely with product stakeholders and users to understand requirements and pain points.
• Take ownership of features from requirements and architecture through development, testing and deployment.
• Provide technical recommendations regarding the future architecture and development of the SaaS platform.

Essential Experience

Software Engineering

• Strong commercial software development background with experience delivering complex applications.
• Strong full stack development capability, with particular strength in backend engineering.
• Experience working with complex, established or legacy software platforms.
• Proven experience analysing, simplifying and refactoring complex codebases.
• Strong understanding of software architecture, design patterns and maintainable coding practices.
• Experience developing APIs, services and system integrations.

Real-Time & Asynchronous Systems

Strong experience in one or more of the following areas:

• Asynchronous software architecture
• Event-driven architecture
• Real-time applications
• Real-time data processing
• Messaging and event-based systems
• Real-time communication protocols
• Distributed systems
• High-volume or data-intensive backend applications
• Experience with technologies or concepts such as WebSockets, MQTT, message queues, publish/subscribe architectures, event streaming or similar real-time communication technologies would be highly relevant.

Databases & Data

• Strong experience working with relational databases, such as SQL-based platforms.
• Experience designing and optimising database structures and queries.
• Experience with time-series databases or time-series data would be highly desirable.
• Understanding of data modelling, performance optimisation and handling high-frequency application data.

Front-End & UX/UI Experience

The successful candidate should have strong product and user-interface(UX/UI design) awareness.

You should have experience:

• Developing modern web-based user interfaces.
• Translating user requirements into effective application interfaces.
• Improving usability of technically complex applications.
• Simplifying complex workflows and presenting technical information clearly.
• Creating responsive, intuitive and visually modern interfaces.
• Working with modern JavaScript/front-end frameworks.
• Collaborating directly with users and stakeholders to understand how they interact with software.
• Developing reusable UI components and maintaining design consistency.
• Experience using tools such as Figma for prototyping or interface design would be advantageous.

Ideal Background

We are particularly interested in candidates who started their careers in software engineering or backend development and have progressively developed strong front-end, product and UX/UI capabilities. Experience within technically complex industries would be particularly valuable, including:

• Telecommunications
• Financial Services / FinTech
• IoT
• Industrial software
• Real-time communications
• Network or infrastructure software
• Engineering applications
• Data-intensive SaaS platforms

Technical Skills

Relevant experience may include:

• Backend software development
• Modern JavaScript / TypeScript
• React, Angular, Vue or similar frameworks
• REST APIs
• WebSockets
• MQTT or similar messaging protocols
• Event-driven architecture
• Message queues / publish-subscribe systems
• SQL and relational databases
• Time-series databases
• Cloud platforms
• Git and modern development workflows
• Automated testing
• CI/CD
• Application performance optimisation

We are not necessarily looking for experience with every technology listed. Strong software engineering fundamentals and experience with complex real-time systems are more important than expertise in a specific technology stack. The ability to quickly understand existing systems and contribute across both back-end engineering and UX/UI is key.