Senior Full-stack Developer, Onninen eCom, K Group

We are strengthening K Group's software development teams by hiring internal software developers for several of Kesko's agile software development teams for the Construction, Building technology, Grocery, and Car Sales businesses. Read more about us: Digital development and IT

We’re looking for two Senior Full-Stack software developers to join the Onninen eCom development team.Whether you're an experienced developer seeking a new challenge or a skilled professional proficient in managing complex systems with multiple deployments, this opportunity might be your next career move.

If you’re passionate about delivering business value, tackling technical debt, and embracing agile—and you’re looking for a solid team, meaningful work, and room to grow—we’d love to hear from you!

The Onninen eCom Team

Our team builds and maintains Onninen’s eCom and digital solutions for Finland, Sweden, Norway, Estonia, Latvia and Lithuania. We’ve developed our own eCom platform, sales tool, and mobile app to support Onninen’s B2B business in these regions.

We work in a distributed, multicultural setup using agile methods. Our focus is on developing front-end interfaces and microservices that connect with back-end systems. We subscribe to a DevOps-philosophy – everyone is empowered to build, improve, and support the platform, not only implementing new features.

Our Team’S Responsibilities:

• Developing and maintaining web applications and services using React, Next.js and Java (Spring). Mobile development is done with React Native
• Interacting with our stakeholders in a multinational environment
• Collaborating with designers and other developers to build high quality user interfaces
• Writing clean, maintainable and efficient code
• Writing the needed automated test cases for the developed functionality (unit testing, E2E, integration / component testing)
• Ensuring our applications are fast, scalable and responsive
• Building and maintaining APIs using Java
• Managing data storage and retrieval using services such as PostgreSQL, Redis and Elasticsearch/OpenSearch
• Participating in code reviews and sharing knowledge within the team
• Keeping up to date with the latest developments in web technologies
• Contributing to our team’s and Kesko’s software development practices

Senior Full-Stack Developer

As a senior full-stack developer, you'll play a crucial role in contributing to the team's backlog. In addition to writing and reviewing code, you'll coordinate with team members and stakeholders to ensure smooth collaboration. Your responsibilities extend beyond your own development work to include reviewing others' code and enhancing our development practices. You'll also assist the Product Owners in maintaining and refining the backlog.

With your extensive experience, you'll be involved in architectural planning and take ownership of the platform's technical needs. As a senior team member, you'll mentor junior developers, fostering teamwork and helping them develop their technical and professional skills. You'll guide them through complex problem-solving processes and encourage best practices.

What We Are Looking For:

• Several years of experience in software development with a larger interdependent system
• Familiarity with writing maintainable and well tested code
• Capable of not only working on given tasks but also contributing to the common platform and making the team better, as whole
• Ability to work independently and collaboratively as part of a team
• Fluent communication in English, which is our working language
• A degree in engineering, major in information technology, software- or web development – or equivalent experience
• You can make it to Kalasatama in Helsinki once a week to be with the team on-site

Tech Buzzword Bingo:

HTML – CSS – React – Next.js – Java (Spring) - JavaScript – TypeScript – React Native –– REST APIs / OpenAPI – CI/CD – Github Actions – GraphQL – Contentful – Elasticsearch/OpenSearch – AWS – Playwright

Bonus points if you have experience in any of these:

• Familiar with Microservices Architecture
• Meta frameworks such as Node.js
• Message queues such as Apache Kafka
• Cloud-based deployment platforms such as AWS, Google Cloud
• Web software monitoring tools such as New Relic, Datadog or Dynatrace
• Implementing A/B testing
• Implementing automated end-to-end tests
• Working with SQL, including writing complex queries, optimizing database performance and designing database schemas.
• Containerization using Docker
• Customer journey and conversion optimization
• ERP and/or CRM process development
• Hardware retail or building contractor experience may help you better understand our customers

The more you know from the above, the more familiar the systems would feel to you from the start. But don’t worry if you don’t have experience with all of them, we’re not looking for unicorns! :)

What We’Re Offering You:

• A truly great team to be part of – diverse, multicultural and professional, yet relaxed and and very easy to work with. We’re not just saying this, you’ll feel it from day one!
• A cool and complex micro-service based omnichannel platform to work with
• The ability to work in a fast-moving environment where your input really matters
• An open work culture where you bring your own ideas to the table, both technically, and improving our services and ways of working as well.
• For office days - modern office with several accommodations (e.g., collaboration and break areas throughout the office, gym, health care services, restaurant and cafeteria…) along good connections in Kalasatama, Helsinki.
• Modern work tools and numerous opportunities to learn and network.
• Extensive employee benefits. These include, among others: Culture & sport benefit (ePassi), shopping benefits that apply in K-Group stores and staff shops, own occupational health care services and leisure time accident insurance. You are also entitled to a car benefit according to our company policy.

Other reasons to join us

The K Group offers attractive opportunities for driving the trading sector forward. You’ll be working in a key function of a leading sector company and innovate solutions for its core operations in the grocery trade, building and technical trade, and car trade.

At K Group, you get to create solutions that make people’s everyday lives easier, with the strength of data gathered from 1.5 million daily customer encounters. You’ll have your finger on the pulse of our consumer and business customers in the grocery trade, building and technical trade and car trade, and get to take part in various interesting projects.

For digital experts with their eye on the future, we offer vast amounts of data and the chance to harness their creativity to improve people’s everyday lives. Our culture encourages reinvention, experimentation, mistakes and learning.

Corporate responsibility is integrated into K Group’s day-to-day activities, and we strive to help our customers make good choices. We want to make life easier for our customers by offering them quality products and services that promote welfare. The focus of our responsibility work is on the welfare of both people and the environment.

We at K Group value diversity and believe that different backgrounds and perspectives are key to success. We strive to create a work environment where everyone has the opportunity to grow. Equality, non-discrimination, and fairness are our core principles in recruitment, compensation, and career development.

Got you interested? Don’t delay applying!

Send your application by 29.10.25, using the application link. We will start contacting and interviewing people as soon as we find suitable candidates, and we’ll be in touch with all the applicants shortly after the application period ends, at the latest.

For inquiries regarding the position, Cristina Vallejo, Developer Team Lead, will be available to receive calls on +358503095720 on October 17th from 13:00 to 14:30, October 21st from 10:00 to 11:00 or October 24th from 10:00 to 11:00.

The chosen candidate is required to take a drug test as part of the pre-employment checks.