Software Engineer

Senior Software Engineer – AI Products, Retail Industry (Helsinki, Hybrid)

Location: Helsinki (Onsite 3 days/week)
Start: ASAP
Duration: Until end of 2025, with possible extension into 2026
Allocation: 100%

Join a high-impact team building cutting-edge, AI-driven recommendation systems used by millions! We’re looking for a Senior Software Engineer to help our client to design, develop, and scale a high-performance API that powers real-time, personalized experiences for over 2.5 million co-op members.

You’ll collaborate with talented data scientists, engineers, and technical leads to bring innovative AI products to life — all in a modern tech environment leveraging Kotlin, Ktor, AWS, Fargate, and containerized infrastructure.

What You’ll Do

Build Scalable APIs: Develop robust, low-latency RESTful APIs in Kotlin using Ktor to serve machine learning model outputs.
Own Cloud Architecture: Design secure and high-performance cloud solutions on AWS.
Collaborate Across Teams: Work hand-in-hand with data scientists and engineers to ensure smooth integration and performance.
Mentor & Guide: Share your expertise in cloud infrastructure and backend best practices with the team.

Your Skillset

10+ years of backend software development experience
Strong Kotlin skills, ideally with production-level experience using Ktor
Proven track record with AWS services and cloud architecture
Hands-on experience with Docker and containerized environments
Expertise in building high-performance, load-intensive systems
Deep understanding of RESTful API principles
Fluent in English and comfortable working in a Finnish-speaking environment
Able to work on-site in Helsinki at least 3 days a week

Bonus Points

Familiarity with other JVM languages
Experience integrating with REST APIs, Kafka, etc.
Exposure to Python and machine learning pipelines
Background in observability, monitoring, or data engineering

This is your chance to leave your mark on a product that reaches millions every single day — while working with cutting-edge AI and cloud technologies in a collaborative, forward-thinking environment.

Apply now and make an impact!

More information from Juho -> juho_witted // juho.sopanen@witted.com