(Senior) Kotlin Engineer (f/m/d)
ZEAL Network SE is a dynamic, international group of companies that has been creating exciting and innovative lottery experiences for over 20 years. As Germany’s largest provider of online lotteries through our brands LOTTO24 and Tipp24, and a trusted partner of Spain’s ONCE, the second-largest national lottery, we’re shaping the future of the lottery industry. We are passionate about driving innovation, as demonstrated by our newest brands, Freiheit+ and Traumhausverlosung, which bring fresh and exciting dreams to life. Additionally, through ZEAL Ventures, we invest in inspiring e-commerce start-ups like Omaze and DAYMADE, fueling fresh ideas and opportunities.
Our team of 350+ professionals from diverse backgrounds is united by a visionary mindset, a passion for collaboration, and a commitment to inspire dreams. At ZEAL, we empower our people to think ambitiously and work together toward a shared purpose: helping people imagine and achieve their aspirations.
As a (Senior) Software Engineer, you will build and evolve backend services that handle player accounts, authentication, and access across our platform. You will develop and improve identity and authorization flows used by multiple business units as well as integrate external verification and regulatory systems to ensure compliance and user safety. The goal is taking ownership of your services in production, ensuring reliability, performance, and maintainability.
Your tasks:
Design, develop, and maintain backend services and APIs, powering player account lifecycle, identity verification, and access management across our multi-tenant platform.
Build and evolve authentication and authorization systems, ensuring secure and easy access for customers across multiple business tenants.
Implement integrations with third-party identity verification providers and regulatory platforms, ensuring compliance and player protection.
Collaborate closely with cross-functional teams: including frontend engineers, compliance specialists, UX experts, customer care, and QA to deliver end-to-end solutions.
Drive API design decisions, ensuring our services are intuitive, well-documented, and aligned with security best practices.
Support production operations: monitoring, troubleshooting, and continuously improving reliability, performance, and auditability of our services.
Participate in technical discussions and knowledge sharing, helping raise the bar for engineering quality and innovation.
What you offer us:
Professional experience in backend development with Kotlin or other JVM languages, ideally with Spring Boot or Micronaut.
Solid understanding of API design principles and experience building microservices or service-oriented architectures.
Experience with relational and document databases (PostgreSQL, MongoDB) and event-driven systems (Kafka).
A security-conscious approach to development, with knowledge of authentication and
authorization patterns (OAuth2, OpenID Connect, session management).Familiarity with containerization and orchestration (Docker, Kubernetes) and cloud platforms (AWS).
A team-oriented mindset: you value collaboration, clear communication, and contributing to shared goals in an agile environment.
Openness to change and a genuine interest in tackling complex, evolving challenges in a regulated industry.
Strong communication skills in English.
Nice to Have
Experience with Go for specific services or tooling.
Exposure to multi-tenant system design and complex business logic with regulatory
constraints.Background in e-commerce, or adjacent regulated digital products.
Familiarity with identity management, know-your-customer processes, or compliance-focused systems.
Frontend experience with Angular.
What we offer:
State-of-the-art technologies and an agile environment (Check our Tech Radar: https://lotto24.github.io/tech-radar/)
A modern, dynamic culture grounded in the success of a leading-edge e-commerce company.
A talented team of ambitious, like-minded colleagues where your knowledge and ideas truly make an impact.
Ongoing personal growth, supported by an annual development budget of €1,500 to invest in your professional development.
Trust and autonomy, no micromanagement, just confidence in your ability to deliver and excel.
Flexible work options with a hybrid setup focused on results.
Unlimited vacation days in addition to your yearly 30-day vacation allowance.
Opportunity for workations abroad using our WorkFlex tool.
Monthly mobility allowance of €30 to use on the mobility option of your choice (e.g., the Deutschlandticket), plus access to a company bike leasing program.
Company pension scheme, provided in partnership with Degura, to support your future financial security.
Subsidized EGYM WELLPASS membership, with a contribution of only €25 per month, giving you access to a wide range of gyms and sports options across Germany.
Monthly company events, team activities, and informal gatherings
Company-wide lunches provided four days a week.