Senior Fullstack Engineer, Retail Media

We are looking for a Senior Fullstack Engineer to join our growing development team working with SOK’s retail media. Your home team will be the Martech team, but you’ll work closely with our e-commerce and applications teams to help our retail media business thrive.

Our exceptional Martech team, about ten internal members plus a few external partners, works closely together, sharing goals and solving challenges with minimal hierarchy. We value high standards and a positive team spirit. Our projects cover a broad range of marketing, measurement, customer communication, and retail media solutions, including ad servers, targeting and measurement, digital analytics and consent management, online-to-offline measurement, multichannel personalized marketing automation, and customer data platforms and activation. We collaborate horizontally across all business units.

About the job

You will be a key member of our enabling team, developing SOK’s retail media capabilities. Your role involves planning, developing, and maintaining retail media ad-serving applications from front to back — ensuring a high-quality user experience across SOK web services.

You’ll collaborate closely with colleagues from different areas of the company. Together with technical product owners, designers, developers, and engineers, you’ll create modern retail media and ad solutions using the latest technologies and best practices.

Key responsibilities:

• Plan, implement, and maintain scalable ad-serving platforms within SOK’s digital services.
• Develop both frontend and backend components to ensure high performance, reliability, and maintainability.
• Build, integrate, and optimize APIs, microservices, and data pipelines related to ad delivery, targeting, and measurement.
• Collaborate with cross-functional teams on system architecture, data models, and technical design decisions.
• Participate in code reviews, testing to ensure code quality and stability.
• Monitor and troubleshoot ad-serving performance issues and contribute to continuous improvement of system scalability and latency.
• Stay up to date with emerging technologies in advertising.

Our workplace is our Helsinki office, Ässäkeskus, where we meet with our colleagues several times a week. When your duties allow, you can also work remotely for part of the week with flexible arrangements.

What we are hoping from you

You have full-stack development experience, strong expertise in modern JavaScript frameworks such as React and React Native, and proficient skills in TypeScript. You are a team player with strong communication skills in English, able to work effectively in a cross-functional, multi-team environment, and curious and eager to learn new technologies.

In addition, we hope from you:

• Experience with Node.js, Express, or a similar backend framework.
• Solid understanding of RESTful APIs, GraphQL APIs, and microservices.
• Cloud, CI/CD, containerization, and serverless architectures.
• Git-based version control.
• Agile development practices.
• Interest in advertising technology.
• Focus on clean and maintainable code.

Nice-to-have:

• Prior experience working in a technical role at a media company.
• Prior experience with advertising or marketing technology platforms.
• Experience with data ingestion, data modeling, or building data pipelines is considered a strong advantage.

What we offer for you

With us, you have an awesome opportunity to improve and influence the daily lives of millions of people. You get to influence and take responsibility; our engineers have a lot of freedom in their work, but they also live with their solutions, and so do millions of users. Here you are creating services directly for the end users, so you are not visiting a project, you own the product. And also:

• Great work is rewarded, and all our employees are included in a performance-based bonus system.
• You will have access to Finland’s most extensive employee benefits, which means discounts on groceries, restaurants, hotels, electronics, cosmetics, rainwear, home appliances, or even car washes. When you work with us, life outside of work becomes a little easier and a lot more enjoyable. You can read more about our benefits here.
• The S Group is Finland’s largest private employer, so opportunities never run out. Our career paths are often long, sometimes winding, but always full of possibilities.
• We are a safe, stable, and Finnish cooperative group. Most of our tax revenue stays in the local area, as does the value generated through procurement and construction. The significant impact of SOK and the entire S Group brings meaningfulness to everyday work.

We in the S Group are committed to fostering a diverse and non-discriminatory working environment where the unique backgrounds, skills, and perspectives of all our employees are respected and valued.

Interested? - We’ll be happy to hear from you!

Please send us your CV and an application highlighting your related skills by 18.1.2026 at the latest. We will actively review applications and invite the most suitable candidates for further discussion. We will notify all applicants about moving forward within two weeks after the deadline.

Our interview process is both respectful and comprehensive. You’ll meet our recruiter, hiring manager and some teammates. We’ll discuss technical things as well as softer skills, validating your technical expertise, and performing a suitability assessment. The aim is to ensure we can offer you what you are looking for and to make sure you’re the right person for the job. Despite the outcome, we strive to make the process a positive one.