Senior Software Engineer — Streaming Platform in London

At FDJ UNITED, we don't just follow the game, we reinvent it. FDJ UNITED is one of Europe's leading betting and gaming operators, with a vast portfolio of iconic brands and a reputation for technological excellence. With more than 5,000 employees and a presence in around fifteen regulated markets, the Group offers a diversified, responsible range of games, both under exclusive rights and open to competition. We set new standards, proving that entertainment and safety can go hand in hand. Here, you'll work alongside a team of passionate individuals dedicated to delivering the best and safest entertaining experiences for our customers every day.

We're looking for bold people who are eager to succeed and ready to level-up the game. If you thrive on innovation, embrace challenges, and want to make a real impact at all levels, FDJ UNITED is your playing field. Join us in shaping the future of gaming. Are you ready to LEVEL-UP THE GAME?

The role

Focussing on our Sportsbook product, we're looking for a Senior Software Engineer to help build and evolve our next-generation trading risk platform, powering real-time liability and exposure management across multiple brands and markets. You'll primarily work on our Core Liability engine — a modular, event-driven system — delivering fast, accurate, and real-time insight into live positions and risk. This platform underpins critical trading decisions and represents a major step forward in scalability, resilience, and streaming architecture across our technology estate.

Key Responsibilities

• Design and build distributed, real-time streaming components within a Flink-based architecture.
• Develop and maintain services that process the full bet lifecycle, from acceptance through settlement, cancellation, and cashout.
• Implement complex financial calculations, including multi-bet and bet-builder logic, ensuring accuracy and consistency at scale.
• Build systems that aggregate exposure and generate real-time risk insights across outcomes, markets, and customers.
• Contribute to a granular alerting framework that detects and publishes meaningful changes in liability.
• Ensure correctness in a high-throughput environment through robust handling of ordering, duplication, and idempotency.
• Optimise streaming jobs for latency, throughput, and resource efficiency.
• Collaborate closely with trading and product teams to translate domain requirements into scalable, reliable systems.
• Contribute to a modular architecture where components evolve independently and scale with increasing demand.
• A real-time liability platform providing live visibility into exposure and risk across brands and jurisdictions.

What You'll Work On

• A Flink-based streaming ecosystem composed of specialised components for ingestion, enrichment, calculation, aggregation, and alerting.
• Event-driven systems that process high volumes of bet events with strong consistency guarantees.
• Outcome-level alerting that enable faster and more informed trading decisions.
• Integration with downstream systems, including trader-facing tools.

Your experience

• 5+ years software engineering experience in building distributed systems.
• Experience with streaming technologies (Apache Flink preferred; Kafka Streams, Spark Streaming, etc.).
• Solid understanding of event-driven architecture and asynchronous processing patterns.
• Experience handling data consistency challenges such as at-least-once processing, idempotency, and event ordering.
• Experience building high-throughput, low-latency systems in production environments.
• Ability to model complex domain logic and translate business requirements into robust technical solutions.
• Experience in cloud computing, ideally AWS.
• Proactive and ability to deal with and account for uncertainty, with the flexibility to learn by iteration.

Nice to Have

• Experience in sports betting, trading platforms, or financial systems.
• Experience building real-time alerting or monitoring systems.
• Exposure to modern data platforms or lakehouse architectures.