Frontend Engineer - Checkout Team

Be a part of the next big thing

Do you thrive on tackling complex challenges? Are you passionate about creating impactful solutions that drive commerce forward? Do you believe in encouraging and elevating those around you?

About us

Kustom, formerly known as Klarna Checkout (KCO), is the Nordic market leader in digital checkout solutions. Today, we support over 24,000 merchants across more than 170 countries, providing a streamlined checkout experience. We offer localized solutions in 18 markets, tailored to specific languages, currencies, and payment methods. No matter where businesses operate, we deliver a checkout experience that meets the needs of both merchants and shoppers - driving growth globally.

The role

We are looking to hire a Frontend Engineer to join our Checkout Product team. In this role, you will be responsible for designing and implementing user interfaces using modern JavaScript frameworks. You will work closely with our designers, product managers and backend engineers to deliver seamless and engaging web applications that optimize user experience and drive conversion.

As a key member of our Checkout team, you'll be at the forefront of crafting exceptional digital experiences. We're not just looking for someone to write code - we're seeking a creative problem-solver who can transform ideas into intuitive, cutting-edge interfaces for our users. Your expertise will help shape the future of our products, making complex flows feel effortless.

At Kustom, you'll have the opportunity to make a real impact on our users' daily interactions. If you're passionate about creating high-performance web applications and thrive on turning ambitious design concepts into reality, we want to hear from you.

Our teams are based in Stockholm, where we prioritize in-person collaboration at our office to foster strong team dynamics.

Things you'll be doing

• Ship features across our checkout products - from the full checkout experience to the embeddable elements library.

• Contribute to Morpheus (our UI library) and the shared design language that holds these products together.

• Help us evolve our embeddable elements built on Web Components, which merchants integrate into very different storefronts.

• Own the performance, reliability, and observability of code that runs in a business-critical path for our merchants.

• Champion good practice in testing, accessibility, and security, and help raise the bar across the team.

• Mentor other engineers, review code and contribute to the technical direction of the frontend.

Skills and experience you'll need

• Bachelor's degree in Computer Science, Engineering, or a related field.

• Deep expertise in modern JavaScript and TypeScript.

• Strong experience with React latest versions and a good grasp of its modern patterns.

• Comfort with a modern build setup (we use the latest Vite), and a willingness to dig into build tooling when it's the right lever.

• Solid foundations in HTML, CSS, and responsive, accessible UI.

• Experience integrating with backend APIs and reasoning about async data flow.

• A component-driven mindset, and experience working with or contributing to a shared design system.

• Experience across the frontend testing spectrum (unit, integration, end-to-end) and a good sense of what's worth testing.

• A production mindset of care about real user experience, performance, error rates and observability.

• Strong communication skills and the ability to work effectively in a dynamic environment.

We believe you'll thrive in this role if you have

• Experience building Web Components or other embeddable widgets that have to live inside someone else's site.

• Familiarity with iframe and cross-origin integration patterns and how to safely run a piece of UI inside another product.

• Experience with localization and building products that work across many markets and languages.

• A background in payments, e-commerce, or any domain where conversion is a first-class metric.

• A genuine interest in User Experience (UX) and how design and engineering decisions shape it.

• Experience with A/B testing and conversion rate optimization (CRO).

• Experience with web performance optimization and Core Web Vitals.

• Experience with Agile/Scrum development methodologies.

Benefits

• Secure your future with a competitive pension package, including both national and occupational pension contributions.

• Comprehensive health coverage with extensive health insurance, long-term illness protection, and flexible salary exchange options.

• Invest in your wellbeing with an annual wellness allowance of 3,000 SEK to spend on the activities that keep you healthy and energized.

• More time to enjoy life with an extra day off when major holidays, such as Christmas Eve or New Year’s Eve, fall on a weekend.

A place to grow

At Kustom, you won’t just be another face in the crowd. This is a place where we elevate each other and celebrate success as a team. We believe in our ability to create excellence - and have fun doing it!

We know we set high expectations, but we also know that the road to success isn’t a straight line. We support and encourage each other to try, to fail, to try again. Because that’s how we grow, individually and together.

Does this sound like the place for you?

About your application

• Please apply in English. At Kustom, we welcome everyone! We don’t care where you’re from, whom you love, or what kind of food is your favorite (unless we’re celebrating together, then we’ll need to know!). We believe in inclusivity for all.

• Given the above, we treat all candidates the same! That’s why we have this awesome recruitment tool to keep track of all the amazing talents that apply - so please; apply through the system and we’ll make sure to keep you updated along the recruitment process. Please note that we can’t keep track of CVs or similar documents sent via email.

• We value your privacy! When you apply, we'll handle your data with care. Want to know more about how we use your information? Check out our FAQs at the bottom of the jobs page - we've got all the details there for you!