Junior Java Developer

Job title: Junior Java Developer – DAX Exchange

Are you an early-career engineer who wants to build high-performance systems that power digital advertising at scale?

As a Junior Java Developer – DAX Exchange at Global, you’ll join a small, focused team building performance-critical services in modern Java. You’ll work on the matching engine that connects advertisers with outdoor screens and, over time, live radio and on-demand audio. You’ll contribute to production code from day one, learning how real-time systems are designed, built and run in the cloud. This is a hybrid role based in our Holborn office in London (3 days per week).

Key Responsibilities

• Backend development (40%): Contribute to the DOOH Scheduler and DAX Exchange, delivering features, fixes and enhancements across the platform using modern Java.

• Quality and reliability (20%): Write clean, well-tested and maintainable code that meets the team’s standards for performance, resilience and observability.

• Operational support (20%): Help monitor, troubleshoot and maintain production services, learning how to support real-time, always-on systems.

• Learning and collaboration (20%): Pair with senior engineers, participate in code reviews and technical discussions, and support continuous improvement in how the team works.

What You’ll Love About This Role

Think Big: Build the matching engine that powers programmatic advertising across outdoor screens in the UK, with growing opportunities across live radio and digital audio.

Own It: Ship code that runs in production, take responsibility for your changes and see the direct impact of your work on a critical platform.

Keep it Simple: Learn to design clear, focused services and straightforward solutions to complex performance and scalability challenges.

Better Together: Work in a small, supportive team where you’ll receive real mentoring, regular feedback and a clear path from junior to mid-level.

What Success Looks Like

In your first few months, you’ll have:

• Contributed working, well-tested code to the matching engine and related services.

• Gained a solid understanding of the DAX platform, its data flows and performance requirements.

• Learned and applied the team’s development practices, tooling and deployment workflows.

• Helped support production systems, including monitoring, debugging and incident follow-up.

• Built strong working relationships with your teammates through pairing, reviews and regular collaboration.

What You’ll Need

• Technical foundations: Experience from a Computer Science (or similar) degree or equivalent practical background, with a strong understanding of core data structures and algorithms.
• Java and OOP fundamentals: Knowledge of Java and core object-oriented concepts (such as inheritance, composition and common design patterns).
• Engineering practices: Familiarity with Git, basic Unix/Linux commands and working within an agile software development environment.
• Attention to detail: A careful, methodical approach to writing, reviewing and testing code.
• Growth mindset: Curiosity about how software interacts with hardware and networks, and an interest in learning more about cloud infrastructure, containerisation and real-time systems.
• Nice to have (but not essential): Interest in low-level performance, networking or systems programming; exposure to AWS or other cloud platforms and/or containerised environments; curiosity about digital advertising, media or high-throughput real-time platforms.

Creating a place we all belong at Global

We are dedicated to creating a place where different voices are represented, amplified and celebrated. We know that we can’t serve our diverse audiences without first celebrating it in our people, which is why we’re passionate about creating an inclusive culture where every Globaller can belong. So, no matter who you are or where you are from, you can find your place at Global.

As a business, we believe in the importance of a healthy work-life balance and the value of a flexible and agile workforce. Therefore, we operate a Smart Working approach. If you need us to make any reasonable adjustments during your recruitment process, drop us an email at [email protected], we’ll be happy to help.