Junior Software Engineer at Sellpy

nShift is the leading global provider of cloud delivery management solutions (SaaS), we enable the frictionless shipment and return of almost one billion shipments across 190 countries each year. We are headquartered in London and Oslo and have over 500 employees across offices in Sweden, Finland, Norway, Denmark, the United Kingdom, Poland, the Netherlands, Belgium, and Romania. Our software is used by many of the world leading e-commerce, retail, manufacturing, and 3PL shippers due to us having over 1000 carriers integrated into our platform, nearly 3 times more than our competitors! If you buy goods online, there is a strong chance that nShift has powered that delivery, so come and join us as we shape the future of shipping, one frictionless journey at a time. About the role We’re looking for a skilled and solution-driven Java Developer to join our Returns team. You’ll help build and evolve the heart of our post-purchase tools – allowing e-commerce websites to offer a smooth returns mechanism and help us ensure it runs reliably at scale. This is a hands-on role where you’ll be involved in everything from design and development to testing, deployment, and monitoring. About you You’re a team player who thrives in collaborative environments but also enjoy working independently when needed. With a structured and solution-oriented mindset, you like solving complex challenges and producing clean, high-quality code. Communication, curiosity, and a positive attitude are key strengths you bring to your work. Responsibilities · Design, develop, test, and release backend features for Returns in line with team and company guidelines. · Build and maintain integrations with e-commerce platforms (e.g. Shopify, Magento, Centra) — including webhooks, authentication, and data imports. · Contribute to architecture and platform decisions (security frameworks, GDPR, architecture, monitoring, CI/CD tools). · Write clean, testable, and reusable code that is scalable and cost-efficient. · Work with modern practices such as code reviews, automated testing, and continuous integration/delivery. · Be an active member of an autonomous team, helping shape both the product and how we work. · Stay up to date with new technologies and proactively suggest improvements for performance and scalability. Required professional experience We are looking for both junior and senior backend engineers with experience in most of the following technologies: · Java · Spring Boot and the Spring ecosystem (Spring Data JPA / Hibernate) · PostgreSQL, including schema migration tooling (Liquibase or Flyway) · AWS (S3, SES, and related services) · CI/CD knowledge such as Jenkins, Bitbucket Pipelines, Docker, etc. · Monitoring tools such as ELK stack or equivalent · Testing: unit testing (JUnit, Mockito), integration testing against mocked external services (WireMock, REST Assured), and performance testing (e.g. JMeter) Nice to have: · Designing and versioning public REST APIs (OpenAPI / Swagger) · Redis and caching strategies · E-commerce or post-purchase domain experience For senior candidates, we additionally value experience working in a large, long-lived codebase — carving out and building modern services alongside a monolith, and driving modernization without disrupting a system that merchants rely on every day. What we’re looking for in you · Strong problem-solving skills with the ability to deliver clean and scalable code. · Service-minded with a positive, proactive attitude. · Comfortable working independently as well as in a collaborative agile team. · Fluent in written and spoken English. Why join us? At nShift, you’ll work on a platform used globally to handle millions of deliveries, solving complex technical challenges with real-world impact. We value knowledge sharing, autonomy, and continuous learning, offering plenty of opportunities to grow your skills while contributing to meaningful projects.

As a Senior Fullstack Engineer, you will be a key player in developing our product, while ensuring our infrastructure and application meet the highest security standards. You'll lead the development of full stack features, mentor junior developers, and take ownership of our application — from implementing new features to planning architectural decisions. You will work with our engineering team at our headquarters in Stockholm, Sweden, collaborating closely with both the product development and operations teams. We are looking for someone who is passionate about building robust, secure systems at scale — managing one of the industry's largest geospatial image datasets, rendering complex 2D and 3D map data, and designing architecture that balances functionality with reliability. You'll contribute to both production engineering and R&D initiatives, helping us maintain trust with our customers while scaling our platform to meet growing demand. In this role, you will: Develop and deliver full stack features for our web application (React frontend) and server-side API (Python backend) Design and implement features across our AWS infrastructure and application layers Plan and evaluate architecture for scalable and reliable infrastructure of a global product Mentor developers in code quality, structure and other best practices Collaborate with the CTO and VP of Engineering to define and improve the product and architecture. Build and maintain geospatial UI systems with interactive 2D and 3D components using React and different map APIs About You‍ You have: Strong problem-solving skills with a track record of overcoming complex programming challenges Extensive expertise in: Backend development SQL/Postgres Experience with: React AWS, GCP or similar Skill for debating tradeoffs for software design decisions, particularly around security and performance Mentorship experience for developers Degree in engineering, computer science, or equivalent experience Excellent written and spoken English It’s an advantage if you also have: Knowledge of IaC and Terraform Worked with web test automation (Playwright) ‍ Why Arkion‍ Impact that matters: your work directly contributes to power grid reliability and supports the energy transition in the society. Real ownership: you’ll shape and influence both product features and system architecture as we scale. Strong and supportive team: you’ll work alongside motivated, collaborative, international colleagues with deep domain and technical expertise. Modern tech-stack: we build AI for power-grid assessment for our customers, and we continuously use and evaluate AI tools built by others to boost our own efficiency; our infrastructure is set up in Terraform and we have a high degree of test automation. Flexible work environment: our company culture accommodates different life circumstances and personal needs. Practicalities Full-time, permanent position located in Stockholm, Sweden. Working hours: Full-time (40 hours/week). Expected start date: as soon as possible, or by agreement. Salary: Competitive salary based on experience. How to apply: Email your CV to arbetsformedlingen@arkion.co with the subject line Senior Fullstack Engineer. A brief note on your motivation for applying is appreciated. Öppen för alla Vi fokuserar på din kompetens, inte dina övriga förutsättningar. Vi är öppna för att anpassa rollen eller arbetsplatsen efter dina behov.