Senior Software Engineer (Node.js, Kafka)

Location: Paris, France Gramian Consultancy is a boutique consultancy specializing in IT professional services and engineering talent solutions. With a strong background in software engineering and leadership, we help companies build high-performing teams by matching them with professionals who truly fit their needs. About the client Our client is a leading player in the online gaming and betting industry, operating one of the largest poker and sports betting platforms in Europe. Their platform serves hundreds of thousands of active users monthly and relies on highly scalable, real-time distributed systems designed to handle massive traffic volumes with high availability and low latency. The company combines strong technical excellence with a fast-moving product environment and offers engineers the opportunity to work on complex distributed architecture challenges at scale. About the Role We are looking for an experienced Senior Backend Engineer to join the Poker engineering team and contribute to the d e sign, development , and optimization of highly scalable microservices powering a large-scale real-time gaming platform. You will work on distributed, event-driven systems handling high-throughput traffic and real-time messaging workloads, while collaborating closely with infrastructure, frontend, data, and security teams. This role is ideal for engineers passionate about backend architecture, scalability, distributed systems, and high-performance platforms. Contract : PERMANENT - CDI Model : Onsite, 4 days week! Location : Paris, France (75007) Hiring Process: 4 interviews - HR screening, 2 Technical Interviews, Final Meeting and Offer Discussion NOTE: high preference for candidates who attended CPGE scientifiques — Classes Préparatoires aux Grandes Écoles scientifiques. Key Responsibilities Design and evolve the architecture of distributed backend systems Develop highly available and scalable microservices Build and maintain APIs and data models Work on real-time event-driven systems with high throughput requirements Implement unit, integration, and end-to-end testing Participate in code reviews and technical discussions Deploy and maintain services in AWS environments Monitor, troubleshoot, and optimize platform performance Contribute to architecture and technical documentation Collaborate with Frontend, Data, Infrastructure, Security, and Product teams Requirements Significant experience in developing back-end services on a high-traffic platform (10K+ req/s) Significant experience with load balancing, high availability, scaling, caching, database, and storage issues Proficiency in event-driven distributed architectures Proficiency in Redis or Kafka (data structures, pub/sub, streams, pipelines) Proficiency in relational databases (MySQL or PostgreSQL), modeling, optimization, transactions, and locks Knowledge of JavaScript and the Node.js ecosystem is desirable (microservices rely on Node.js) Knowledge of the cloud environment DevOps culture (CI/CD, Docker, Observability) Mandatory academic background from CPGE scientifiques (Maths Sup / Maths Spé) Benefits Permanent full-time contract (CDI) 4-day work week Profit-sharing and participation programs Company restaurant On-site gym facilities Long-term growth opportunities Modern engineering culture focused on scalability and innovation