Senior Backend Engineer / Kotlin

About the project

Join to Appunite to shape the future of out-of-home delivery for our client. We are building platform – a scalable, high-performance system that empowers carriers across Europe to deploy and optimize parcel locker networks.

In this role, you will work at the intersection of startup agility and enterprise scale. We move fast, experiment freely, and take full ownership of our work. We don't just "write code"; we solve real-world logistics challenges by building reliable backend systems that make global delivery smarter and more connected.

If you love turning complex architectural puzzles into elegant technical solutions, let’s build the future of logistics together!

This offer is planned for six months.

Senior: 19,500-26,500 PLN net/month B2B

Job requirements

What do we need for this position?

Design and maintain server-side applications with a focus on high availability and scalability.
Collaborate in a product trio, working closely with designers and product managers to ship impactful features.
Drive technical excellence by promoting best practices in code quality, security, and automated testing.
Proactively troubleshoot and optimize existing systems to ensure top-tier performance.
Stay curious – research emerging technologies and help us innovate our tech stack.

You’ll be a great fit if you have:

5+ years of experience as a Backend Engineer in cross-functional, agile environments.
Strong proficiency in Kotlin for backend development.
Hands-on experience with Spring Boot, building robust and scalable services.
Solid SQL skills, including schema design and performance tuning for relational databases.
Experience with event-driven architectures (e.g., Kafka, SNS/SQS).
Proficiency in REST API design and microservices architecture within cloud environments (preferably AWS).
Familiarity with DevOps tools, specifically Docker and Kubernetes.
Excellent communication skills in English (C1) and Polish, with the ability to explain complex technical concepts to various stakeholders.

Nice to have:

Experience in the logistics or e-commerce sector.
Knowledge of Infrastructure as Code (Terraform/CloudFormation).
Ability to lead technical workshops or mentor junior developers.

Our recruitment process is only 3 steps long:

Culture & mission fit meeting with Recruitment Team (abt 45 minutes)
Competency interview with team representatives (abt 60 minutes)
Technical task specified by the client
Competency interview with Client (abt 30 minutes)
If any other step of the recruitment process is necessary, we will inform you!
And finally, the decision, after which we can say “welcome on board.”