Senior Frontend Developer

Happy Horizon builds digital products and platforms for clients across retail, healthcare, and public services. You will join our Technology studio in Gennep, working in a cross-functional squad with UX designers, backend engineers, and QA. Your focus is the client-facing layer: accessible interfaces, performant component libraries, and reliable integrations with headless CMS and commerce APIs. You will take ownership of technical decisions within your squad, review pull requests, and help junior developers grow through pairing and clear documentation. Most delivery happens in two-week sprints with regular client demos. You will collaborate closely with strategists when requirements shift, and with our media team when campaign landing pages need to ship on tight timelines. The work is varied, but always grounded in maintainable code and measurable user outcomes. What you bring Five or more years of professional experience building web applications with TypeScript and a modern framework such as React or Vue Strong understanding of semantic HTML, CSS architecture, and WCAG-oriented accessibility practices Experience integrating REST or GraphQL APIs and working with design systems or component libraries Comfortable writing unit and integration tests and participating in code reviews Clear communication in English; Dutch is a plus when working with local stakeholders Pragmatic mindset: you balance quality with delivery deadlines without cutting corners on security or accessibility