Senior Frontend Engineer - Checkout (all genders)

ABOUT YOU; Hamburg; On-site; EUR 85,000 - 120,000; Full time

Job summary

SCAYLE’s Frontend Team builds the embeddable checkout, authentication and express-checkout web components for our in-house Checkout as a Service platform. 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.

Architecting and building modular checkout UI components in TypeScript and React, managing state with Redux Toolkit and

Qualifications

• 5+ years frontend engineering experience with senior-level ownership in enterprise-scale setups.
• Mastering modern JavaScript (ES6+) and TypeScript in strict mode.
• Good experience with Flutter.
• Building complex UIs with React 19, Redux Toolkit, and redux-saga, handling async flows and redirects.
• Optimizing Web Performance and Core Web Vitals for fast loading and high conversion.
• Semantic HTML5 and scalable CSS architectures using SCSS, BEM, and design systems.
• Developing multi-tenant, internationalized UIs using Formik and react-intl.
• Writing automated tests with Jest and React Testing Library; working in CI/CD pipelines.
• Balancing technical excellence with business priorities and pragmatic trade-offs.
• Clear communication in English; proactive blockers in an agile environment.

Responsibilities

• Architecting and building modular checkout UI components in TypeScript and React; managing state with Redux Toolkit and redux-saga.
• Developing payment provider integrations (e.g., Klarna, PayPal, Apple Pay) including widget/redirect flows.
• Owning storefront integration contracts for multi-tenant setups and embedding web components.
• Optimizing Core Web Vitals, loading speeds, and rendering performance to boost conversions.
• Monitoring production issues across tenant shops using observability tools like Datadog.
• Ensuring WCAG accessibility, responsive design, and cross-browser compatibility.
• Collaborating with Product, UX, Backend, and QA in daily agile workflows to ship features.
• Driving engineering standards through code reviews, architecture discussions, and refactoring.
• Expanding platform capabilities to support client customization via injectable content.

Skills

Frontend engineering

JavaScript/TypeScript

React

Redux Toolkit

Redux-Saga

Flutter

Web performance

HTML/CSS

Formik/react-intl

Testing (Jest RTL)

CI/CD

Accessibility WCAG

Agile

Tools

Jest

React Testing Library

CI/CD

Job description

Company Description

SCAYLE stands for innovation, international collaboration, and a strong focus on data. We believe that stepping outside of our comfort zone and making bold decisions is key to growing both professionally and personally. Instead of seeing problems as obstacles, we approach them as opportunities to find better solutions. We work in an environment that encourages flexibility, creativity, and continuous development. What drives us is the shared motivation to make an impact and actively shape the future of eCommerce.

Company Description

SCAYLE stands for innovation, international collaboration, and a strong focus on data. We believe that stepping outside of our comfort zone and making bold decisions is key to growing both professionally and personally. Instead of seeing problems as obstacles, we approach them as opportunities to find better solutions. We work in an environment that encourages flexibility, creativity, and continuous development. What drives us is the shared motivation to make an impact and actively shape the future of eCommerce.

Job Description

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
• Collaboration 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

Qualifications

• 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
• Good experience with Flutter
• 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

Your perks at a glance: Visit our benefits page.

(Please note that benefits may vary depending on the location)

A Place Where You Can Be You

We take it as our responsibility to create an environment where everyone feels welcome, exactly as they are.

Different backgrounds and perspectives make us stronger and shape our culture in ways that matter.

What we stand for internally, we stand for as a brand: acceptance, inclusion, and fairness.