Senior Frontend Engineer - Checkout (all genders)

SCAYLE GmbH; Hamburg; Hybrid; EUR 70,000 - 85,000; Full time

Job summary

SCAYLE GmbH is a leader in embeddable checkout and eCommerce infrastructure. The Senior Frontend Engineer for Checkout will architect and implement modular UI components in TypeScript and React, and own payment provider integrations across multi-tenant storefronts, ensuring fast, reliable user experiences.

You will collaborate with Product, UX, Backend, and QA teams, optimize performance, and contribute to core platform capabilities for a scalable checkout ecosystem.

Qualifications

• 5+ years of frontend engineering experience.
• Building complex UIs with React 19, Redux Toolkit, and redux-saga; handling async flows and multi-step funnels.
• 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 forms-heavy, internationalized UIs with Formik and react-intl in multi-tenant REST API environments.
• Writing automated tests with Jest and React Testing Library; using modern CI/CD pipelines.

Responsibilities

• Architecting and building modular checkout UI components in TypeScript and React.
• Developing payment provider integrations (Klarna, PayPal, Apple Pay) including widget and redirect flows.
• Owning storefront integration contracts for multi-tenant setups with embeddable web components.
• Optimizing Core Web Vitals and rendering performance to drive conversions.
• Monitoring production issues with observability tools like Datadog.
• Collaborating with Product, UX, Backend, and QA in daily agile workflows to ship features.

Skills

TypeScript

React

Redux Toolkit

redux-saga

Frontend architecture

Performance optimization

Cross-functional collaboration

English communication

Tools

Datadog

Jest

React Testing Library

Formik

react-intl

CI/CD pipelines

Job description

Senior Frontend Engineer - Checkout (all genders)

• Full-time
• Compensation: EUR 70,000 - EUR 85,000 - yearly

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.

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
• 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)
• 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 .
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.