Web Developer

Avanti are looking for a Software Developer to work with a company based in Swindon. Salary is £35-45k. Company overview Join a growing B2B SaaS company building a commercially successful platform for enterprise customers. We use modern .NET technologies and a React front end, and we prioritise robustness, performance and accessibility. This role is with a small but expanding in-house engineering team where your work will have visible impact. Location & working pattern Hybrid: office-based minimum 3 days per week (commutable to the Swindon area). Full-time, permanent. Role overview We’re looking for an experienced Web Developer to help evolve and modernise our established SaaS platform. You’ll own front-end work, drive a gradual migration from older .NET UI patterns to modern MVC React, build reusable UI components and collaborate closely with backend engineers, designers and product managers. Key responsibilities * Maintain and enhance an existing .NET WebForms UI while driving an incremental migration to ASP.NET MVC/Razor and React components. * Build and refine React features (components, hooks, routing, forms, error boundaries and user flows). * Consume ASP.NET Core APIs from the front end: data fetching, caching strategies, optimistic updates and resilient error handling. * Create and maintain a reusable component library / design system; manage CSS architecture (SCSS modules or utility CSS), responsive layouts and theming. * Ensure accessibility (WCAG-aligned) and semantic HTML, including keyboard navigation and ARIA patterns. * Optimize front-end performance: code splitting, lazy loading, asset/image optimisation and Lighthouse remediation. * Implement client-side auth flows (e.g., OIDC), protected routes and session state. * Write and maintain front-end tests (unit/integration and E2E). * Own front-end tooling and developer experience. * Collaborate with backend engineers on API contracts and UX acceptance criteria with designers/PMs. Essential skills & experience * Practical experience maintaining ASP.NET WebForms UIs (pages/controls, ViewState, server controls) and authoring ASP.NET MVC/Razor views. * Strong React skills (TypeScript preferred): components, hooks, routing, state, forms and error boundaries. * Solid web fundamentals: HTML5, CSS3 (Flexbox/Grid), responsive design, JavaScript/TypeScript (ES2020), cross-browser compatibility. * Hands-on accessibility experience (WCAG-aligned). * Performance-first mindset (Core Web Vitals): code splitting, lazy loading, bundle analysis. * Experience calling REST APIs securely from the browser, handling auth tokens/refresh and robust error UX. * Testing: Jest React Testing Library for unit/integration; Playwright or Cypress for E2E. * Familiar with modern tooling (npm/yarn/pnpm, Vite/Webpack, ESLint/Prettier, type-checks). * Comfortable shaping UI requirements with designers/PMs and aligning API contracts with backend teams. Desirable * Exposure to Blazor (Server or WebAssembly). * Experience building design systems (Storybook, tokens), Tailwind or SCSS architecture. * Experience with incremental UI migrations (WebForms → MVC/Razor React). * Familiarity with SEO basics for SPAs, instrumentation/analytics and internationalisation. * Experience using AI coding assistants responsibly (e.g., Copilot) while critically reviewing output. Education & experience Proven track record shipping production web UIs in a .NET React environment. Degree in Computer Science / Engineering or equivalent practical experience; portfolio or GitHub desirable. Apply now if interested

Location: Swindon, Wiltshire, GB

Posted Date: 11/7/2025