About the RoleWe're looking for a Senior Backend Developer who thrives in a deeply hand-on environment and enjoys being close to the code on a daily basis. This role is heavily focused on building, optimising, and scaling backend services in a high-load system where performance and reliability are critical.You'll be working on complex, real-time challenges at the core of our platform - improving latency, ensuring high availability, and making systems more efficient at scale. This is not a coordination-heavy role; it's for someone who enjoys writing production code, solving tough engineering problems, and seeing the direct impact of their work.If you're product-driven, take ownership, and prefer a "build first, improve fast" approach while working on systems where every millisecond matters - this role will feel like home.Key ResponsibilitiesWork as part of a cross-functional team owning a core product within the platformDesign, build, and deliver new backend features end-to-end in a distributed environmentWrite high-quality, production-level code daily, contributing directly to a high-load, scalable systemTake ownership of services handling financial transactions at scale, with a strong focus on reliability and accuracyProactively suggest and implement improvements in architecture, processes, and development practicesParticipate in code and architectural reviews to maintain high engineering standardsSolve complex business and technical challenges with pragmatic, efficient solutionsParticipating in on-call rotations within the squad to ensure the reliability and availability of our systemsPlay an active role in ongoing tech transformation initiatives across the platformCollaborate closely with engineers, product,



and other stakeholders to deliver impactful solutions used by millions globallyRequirementsSolid experience with Node.Js/TypeScript is adecuado, but we also welcome experts in other OOP languages such as Java, Python, C++, C#, or GoStrong understanding of asynchronous programming techniquesDeep production experience with Kafka: confident reasoning about consumer-group rebalances and their impact on in-flight processing, offset-commit strategies under retries and duplicate delivery, and the limits of "exactly-once" semanticsExperience designing idempotent, retry-safe handlers for at-least-once pipelines: transactional outbox, idempotency keys, and deduplicationExperience building services with gRPC or similar RPC frameworksStrong knowledge of relational databases such as MySQL or PostgreSQL, plus production experience with at least one NoSQL technology at scale, such as DynamoDB, MongoDB, or RedisHands-on experience running services on Kubernetes and AWS/GCP: deployment, autoscaling, resource limits, and production debuggingProduction operations experience: on-call ownership of a high-load system, including incident response, impact assessment, root-cause analysis, and post-incident improvementsNice to HaveExperience with ClickHouse or other columnar/analytical databasesExperience with multi-region / failover architectures: data replication, regional isolation, and graceful degradationPractical use of AI coding agents such as Cursor or Claude Code as part of daily development: effective prompting, reviewing, and validating AI-generated codeUnderstanding of application security and industry best practicesGambling domain experienceWhat We OfferCompetitive SalaryQuarterly BonusesUnlimited Paid Time OffUnlimited Paid Sick LeaveRemote & Flexible WorkingPrivate Medical InsuranceFinancial Support for Life EventsProfessional Development BudgetInternational ExposureRegular Company Events*Benefits may vary depending on location and contractual agreement#J-18808-Ljbffr

📌 Senior Backend Engineer (Core Team) (Barcelona)
🏢 Playson
📍 Barcelona