Senior Backend Developer (m/f/x)

5G Systems GmbH; Wien; On-site; EUR 72,000 - 88,000; Full time

Benefits offered by this job

Competitive salary

International group

Responsibility

Career development

Team events

Corporate benefits

One team culture

Job summary

5G Systems GmbH, based in Vienna, is seeking a Senior Backend Developer (m/f/x) to design high‑performing Java services in a complex system landscape. You will contribute to new technology stacks and maintain existing legacy systems while collaborating across teams in a cloud‑first environment.

The role emphasizes architecture, scalability, and data integrity, with a strong focus on quality and continuous learning. An international group with competitive remuneration awaits the right candidate.

Qualifications

• Bachelor’s or Master’s degree in Computer Science or related field.
• 5+ years of professional software development experience.
• Experience with processing money transactions in Casino/Sportsbook/FinTech environments is a plus.
• Experience with fault‑tolerant architectures with strong data consistency and idempotency guarantees.
• Strong development skills in Java 18–25 or .NET; ability to build scalable systems.
• Cloud experience with AWS or Azure.
• Strong database fundamentals; performance tuning and indexing.
• Experience with MongoDB; knowledge of ClickHouse or analytical SQL is a plus.
• Knowledge of containers (Docker) and orchestration (Kubernetes).
• Basic Linux knowledge.
• Fluent English communication.
• Focus on quality and root‑cause problem solving.

Responsibilities

• Design high‑performing Java‑based services in a complex landscape.
• Contribute to concept, design and implementation of modern software solutions.
• Maintain legacy systems while adopting new tech stacks.
• Lead projects from draft to production deployment.
• Document software architectures and transfer knowledge within the team.
• Mentor and develop junior team members; promote teamwork and learning.
• Participate in code and design reviews to raise quality.

Skills

Java backend development

Cloud computing

English communication

Problem solving

Team leadership

SQL optimization

Education

Bachelor's or Master’s in CS/related

Tools

AWS

Azure

MongoDB

ClickHouse

Linux

Docker

Kubernetes

Job description

We are 5G Systems, a technology company based in the heart of Vienna and part of the Tipico Group, Germany’s leading sports betting provider and part of Banijay Gaming, a European champion in sports betting and online gaming. We approach every challenge like a Championship match, with a mission to excite the arena and elevate the betting experience for every customer. Our culture is energetic and ambitious - we play as a team to win high, leave an impact, and commit to excellence. Fueled by our passion for the perfect product, we use the newest tech stack to get better every single day.

At 5G Systems, we believe in owning our game. Are you ready to shape the technology behind one of the industry's leading gaming businesses and make an impact? Then show us your game face - because we're looking for a Senior Backend Developer (m/f/x) to join our team!

Your playing field:

• We love what we do: You will design high performing Java-based services in a complex system landscape.
• You will be involved in the concept, design and implementation of modern software solutions.
• You will contribute to our new technology stack as well as maintaining the existing legacy system.
• Together as one team: You will accompany software projects from draft until running them on production.
• Documentation of software-architectures and know-how-transfer belongs to your tasks.
• You will coach and develop more junior team members as we believe in sharing information and learning from each other - we are as strong as our team is.
• Your passion for code and design reviews is your strength to make us better than we were yesterday.

Which skills you should bring to the pitch:

• Education. You have a Bachelor’s or Master’s degree and at least 5 years of proven professional experience in Software Development.
• Experience. Ideally, you bring a solid background in processing money transactions within Casino, Sportsbook or FinTech environments.
• Architecture. You have experience with fault‑tolerant architectures with strong data consistency and idempotency guarantees.
• Development. You have strong development skills in Java 18‑25 or .NET, enjoy solving complex problems and know how to build scalable systems.
• Cloud. You’ll be working in a cloud‑first environment, so hands‑on experience with AWS or Azure is key.
• Databases. You have strong database fundamentals, with a focus on performance engineering, query optimization and execution plan analysis, as well as expertise in indexing strategies such as composite, covering and partial indexes.
• Storage. You understand storage‑aware design, including how to balance read and write loads and design schemas that remain fast at scale.
• MongoDB. Experience with MongoDB is a strong advantage. Experience with ClickHouse or analytical SQL is nice to have.
• Containers. You have knowledge of virtualization and containerized applications.
• Linux. You have basic knowledge of Linux.
• English. You have a good command of English. Our team consists of more than 50 different nationalities working together to achieve Tipico’s mission, and English is how we communicate across the company.
• Quality. You care about doing things right, and that starts with understanding them deeply.
• Problem‑solving. You solve problems by understanding their root cause, not just their symptoms.

This is how we score with you:

• Fair remuneration. We offer a competitive salary package, the annual base salary for this position in full‑time starts from 80,000 Euro. The actual offer will depend on your skills and experience and can be higher.
• Established international Group. We have a solid foundation on which you can grow.
• Responsibility. You have a responsible position in an exciting and dynamic industry at Germany’s #1
• Personal and professional development. We offer you the opportunity to develop and grow to realize your full potential.
• Team spirit. With us, you will experience a working environment with a familiar working atmosphere and regular company and team events.
• Corporate Benefits. Get access to over 1,500 exclusive offers from top brands.
• One team culture. We believe in teamwork and team spirit, but we also value the uniqueness of each and every one of us. Together we are stronger.

Think a career at 5G Systems' right for you?

We look forward to your application!