Senior Backend Engineer

Kustom; Stockholms kommun; On-site; SEK 900,000 - 1,300,000; Full time

Benefits offered by this job

Pension plan

Comprehensive health insurance

Wellness allowance 3000 SEK

Extra day off on major holidays

Job summary

Kustom is seeking a Backend Engineer to design and implement robust server-side solutions powering our Nordic digital checkout. In Stockholm-based teams you'll work with product managers and engineers to deliver high-performance, scalable applications that underlie our core payments platform.

You'll mentor peers, contribute to architectural decisions, and help shape our technical roadmap while maintaining a strong focus on reliability, security, and code quality in a fast-growing environment.

Qualifications

• Bachelor’s degree in Computer Science, Engineering, or a related field.
• 7+ years of professional backend development experience.
• Deep expertise in Java.
• Strong knowledge of Spring Framework and Spring Boot.
• Extensive experience with AWS cloud services and microservices architecture.
• Excellent understanding of database design and performance optimization.
• Experience with RESTful APIs and API security.
• Proven experience in leading and mentoring engineers.

Responsibilities

• Implement scalable, high-performance backend services powering our global payment infrastructure.
• Lead technical discussions and mentor junior team members while contributing to architectural decisions.
• Drive engineering excellence through code reviews, best practices, and documentation.
• Collaborate with Product and Design to implement robust technical solutions.
• Contribute to the technical roadmap and help shape the future of our platform.

Skills

Java

Spring Framework

Spring Boot

AWS

Distributed systems

REST APIs

Git & GitHub

API security

Technical leadership

Education

Bachelor’s degree in Computer Science, Engineering, or a related field

Tools

Git & GitHub

Job description

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? Are you someone who believes 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 your business operates, 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 Backend Engineer to join our development team. In this role, you will be responsible for designing and implementing robust server-side solutions using modern technologies and frameworks. You will work closely with product managers and fellow engineers to deliver high-performance, scalable applications that power our core business infrastructure.

As an integral part of our development team, you'll play a crucial role in developing and maintaining our essential backend infrastructure. We need a detailed oriented person who can design and implement efficient, future-proof solutions for complex business problems. Your knowledge and vision will be instrumental in building a solid technical foundation that ensures our product remains reliable and performant as we grow.

Here at Kustom, you'll get to drive innovation, and leave your mark on our technical architecture. As part of our cross-functional Agile team, you'll collaborate with talented peers to create digital products that revolutionize how merchants worldwide conduct their business.

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

Things you'll be doing

• Implement scalable, high-performance backend services that power our global payment infrastructure
• Lead technical discussions and mentor junior team members while contributing to architectural decisions
• Drive engineering excellence through code reviews, best practices, and technical documentation
• Work closely with Product and Design to implement robust technical solutions
• Contribute to our technical roadmap and help shape the future of our platform

Skills And Experience You'll Need

• Bachelor’s degree in Computer Science, Engineering, or a related field.
• 7+ years of professional experience in Backend development, with deep expertise in Java
• Strong track record of designing and implementing large-scale distributed systems
• Advanced knowledge of Spring Framework and Spring Boot
• Extensive experience with AWS cloud services and microservices architecture
• Expert-level understanding of database design, optimization, and various storage solutions
• Proven experience with Git and Github for version control and team collaboration
• Deep understanding of RESTful APIs, API security, and performance optimization

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

• Strong technical leadership skills with a track record of mentoring junior engineers
• Passion for solving complex engineering challenges and driving technical innovation
• Experience with high-throughput, low-latency systems is a plus
• Excellent communication skills and ability to explain complex technical concepts clearly
• Track record of driving technical initiatives and improving system architecture
• Strong commitment to code quality, testing, and technical documentation
• Ability to balance technical excellence with practical business needs

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’re not going to be just 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!

And 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?