Senior Frontend Engineer - Checkout (all genders)

The Frontend Team builds the embeddable checkout, authentication and express-checkout web components behind SCAYLE’s Checkout as a Service which is our in-house eCommerce infrastructure licensed to online retailers. Tenant storefronts integrate them as a drop-in script, and the components own everything the customer sees from entering the checkout to order confirmation: authentication, addresses, payment selection and order placement, across many shops, countries and payment providers.

• Architecting and building modular checkout UI components in TypeScript and React, managing state and side effects with Redux Toolkit and redux-saga

• Developing payment provider integrations (e.g., Klarna, PayPal, Apple Pay), including widget and redirect flows

• Owning storefront integration contracts for multi-tenant setups, including embeddable web components, host events, and tracking

• Optimizing Core Web Vitals, loading speeds, and rendering performance to drive conversion rates and elevate user experience

• Monitoring and resolving production issues across tenant shops using observability tools like Datadog

• Translating complex checkout requirements into scalable solutions while ensuring WCAG accessibility, responsive design, and cross-browser compatibility

• Collaborating cross-functionally with Product, UX, Backend, and QA teams in daily agile workflows to ship features like one-page or multi-step checkout flows

• Driving engineering standards through thorough code reviews, architectural discussions, and technical refactoring initiatives

• Expanding core platform capabilities (e.g., for the SCAYLE checkout ecosystem) to enable client customization through injectable content

• 5+ years of frontend engineering experience with senior-level ownership (including enterprise-level experience or leading complex frontend setups)

• Mastering modern JavaScript (ES6+) and advanced TypeScript in strict mode

• Building complex UIs with React 19, Redux Toolkit, and redux-saga, handling asynchronous flows, multi-step funnels, and payment redirects

• Optimizing Web Performance and Core Web Vitals to ensure fast loading speeds and high conversion rates

• Crafting semantic HTML5 and scalable CSS architectures using SCSS, BEM, and modern design systems

• Developing forms-heavy, internationalized UIs using tools like Formik and react-intl in multi-tenant REST API environments

• Writing automated tests (Jest, React Testing Library) and working within modern CI/CD pipelines

• Balancing technical excellence with business priorities, making pragmatic trade-offs to deliver value without over-engineering

• Communicating with transparency and ownership, proactively raising blockers in fluent English, collaborating across disciplines, and adapting in an agile environment

Nice to have

• Experience building embeddable widgets / web components or other frontends that run inside third-party sites

• Business smartness: enterprise-level experience, comfortable talking to C-level

• Flutter skills

70000 - 85000 EUR