If you are a Full Stack JavaScript Developer with a proven track record of developing single-page applications, we have a new role we would like to discuss with you. Please note this role requires onsite attendance four days a week in Upminster, Essex. The client is building a platform that guides consumers through the complete online customer journey, from their first visit through identity verification, e-signature and submission. As a Mid-Level Full-Stack JavaScript Developer, you''ll work across the platform: a React single-page application on the front end, Node.js APIs and background workers on the back end, and Microsoft SQL Server as the system of record. This is a hands-on product engineering role where you''ll ship customer-facing journey steps, build and consume REST APIs, write database migrations and integrate third-party services behind clean, maintainable interfaces. What you''ll do Build and maintain customer-journey screens and shared components in React 19, using React Router 7, Vite and Sass/SCSS across multiple branded sites from a single codebase. Develop back-end features in Node.js, including a Fastify API, an Express backend-for-frontend and durable background jobs processed through a SQL-backed outbox queue. Design and evolve the SQL Server schema through forward-only migrations, using parameterised queries and transactional business logic. Integrate and mock third-party services, including identity-verification and lead-management providers, ..... full job details .....