Senior Front End Developer in Hatfield

About us: Mitsubishi Electric is a global innovator in energy, automation and building technologies. From air conditioning and lifts to robotics and power systems that power homes and businesses across the UK. With 150,000 employees worldwide and 850 in the UK, we’re creating “Changes for the Better.” Join us to make a real impact for a smarter, sustainable future.

Role summary: A Senior UI Developer responsible for designing, building, and evolving scalable, high-quality user interfaces across web and mobile platforms. They lead front-end architecture decisions, establish UI engineering standards, and collaborate closely with backend, DevOps, and QA teams to deliver performant, accessible, and maintainable applications. This role operates across Blazor, .NET 9/10, TypeScript, MAUI, Web Components, HTML, and CSS, within cloud-hosted, distributed systems running on AWS.

Skills/Responsibilities:

• Expert-level knowledge of HTML, CSS, JavaScript/TypeScript, and modern browser APIs.
• Strong experience with SPA frameworks such as Blazor (Server & WebAssembly), Angular, or React.
• Familiarity with .NET MAUI or similar hybrid mobile frameworks.
• Solid understanding of Web Components (Custom Elements, Shadow DOM, Templates).
• Experience integrating with RESTful APIs.
• Design and build scalable, component-driven UI architectures.
• Develop reusable UI components and shared libraries.
• Apply best practices in component composition, state management, and UI modularisation.
• Ensure interoperability between modern frameworks and Web Components.
• Deep understanding of DOM lifecycle, browser APIs, and rendering behaviour.
• Implement accessible, standards-compliant UI (WCAG, ARIA, semantic HTML).
• Apply progressive enhancement principles.
• Optimise frontend performance through efficient rendering, lazy loading, and bundle size reduction.
• Diagnose and resolve performance bottlenecks and memory leaks.
• Ensure responsive, mobile-first design and cross-browser compatibility.
• Build and maintain cross-platform UI for web and mobile environments.
• Share UI components across platforms and implement platform-specific enhancements.
• Handle device capabilities and native integrations.
• Design UI solutions that support asynchronous and event-driven systems.
• Integrate with backend services using REST APIs and authentication flows (JWT, OAuth).
• Understand and troubleshoot issues across frontend–backend boundaries.
• Work with cloud-based and event-driven architectures (e.g. AWS services).

Experience:

• 6+ years of professional experience in frontend or full-stack development.
• Proven experience architecting and delivering large-scale UI applications.
• Strong track record of building and maintaining reusable component libraries and design systems.
• Experience working within Agile development environments.
• Demonstrated ability to own features end-to-end, from design through to delivery.
• Experience collaborating across engineering, product, and design teams.
• Exposure to cloud platforms (particularly AWS) and modern deployment environments.
• Experience working on performance-critical and user-focused applications.

In return for your commitment, we will offer you some fantastic benefits:

• Generous annual leave allowance - 25 days per year, plus bank holidays increasing by one day with each year of service until 27 days per year.
• Flexible Working - we offer a range of flexible working options that include working from home or hybrid working.
• Pension.
• Life Assurance.
• Group Income Protection Scheme.
• Private Medical, Dental Insurance and a Cash Plan Scheme - Single cover funded by Mitsubishi.
• Access to Mitsubishi’s very own discount platform.
• Colleague Referral Scheme.
• Holiday Buy.
• Long Service Awards.
• Cycle to Work Scheme.
• Sports & Social Club (Recent events such as theatre trips, Ascot, Paintball, The Darts).
• Employee Assistance Programme including additional services Eldercare & Best Doctors.

Equality and Diversity: As the business environment around Mitsubishi Electric Group is rapidly changing, providing a workplace where employees can work to their full potential regardless of gender or age is essential to business development. Based on this, Mitsubishi Electric promotes employee diversity through the following measures.