Senior Backend Developer

Build the backend services behind a real-time gaming platform processing tens of thousands of messages every second. Senior Backend Developer - Real-Time Platform Paris, France · Permanent · On-site What you'd actually work on Designing highly available backend architecture for a real-time transactional platform Building and maintaining scalable microservices using server-side JavaScript Developing APIs and data models used by the platform's core services Contributing to a communication gateway handling authentication, flow control, routing, and asynchronous messaging Developing user registration services capable of absorbing significant traffic peaks Adding new functionality and mechanics to the platform's core engine Improving application performance, scalability, and resource usage Designing automated unit, functional, integration, and load tests Reviewing code and contributing to shared engineering standards Deploying services on managed cloud infrastructure Implementing monitoring and investigating production performance Maintaining technical and architectural documentation Working with frontend, data, infrastructure, security, and project teams Where it gets technically interesting A communication gateway processing tens of thousands of messages per second Event-driven services where ordering, retries, duplicate messages, and partial failures must be managed explicitly Server-side JavaScript used for concurrent, high-throughput systems beyond standard web applications Services that must absorb sudden traffic peaks without affecting availability Asynchronous messaging and in-memory data structures supporting real-time application flows Relational databases operating under concurrent transactional workloads Query optimisation, transaction boundaries, and lock management under contention Caching and load-distribution decisions that directly affect performance and consistency A modular platform requiring continuous availability and strict protection of user data What we're looking for 5+ years of experience building and operating backend services in production Strong experience with server-side JavaScript and Node.js Experience developing services that handle high request or message volumes Good understanding of high availability, load distribution, scalability, and caching Experience designing microservices and event-driven architectures Strong knowledge of asynchronous messaging systems and in-memory data structures Experience with relational data modelling and complex query optimisation Understanding of transactions, concurrency, locking, and data consistency Practical experience with automated unit, functional, integration, and load testing Knowledge of containers, continuous deployment pipelines, and monitoring tools Ability to investigate performance and production issues across multiple technical layers A Master's degree or equivalent technical background The company A European digital entertainment company operating high-volume online platforms across several markets. The organisation employs approximately 500 people and serves hundreds of thousands of active users. Its proprietary transactional platform supports real-time activity, personalised user experiences, and fraud prevention while maintaining strict availability and data protection requirements. Health insurance, profit-sharing, and an employee incentive scheme. Languages: Native or bilingual French and professional English. A search run by The French Sourcer, recruitment built for technical teams.