Back End Developer

Robert Half Technology are assisting a leading UK media organisation to recruit a Backend Engineer on a 6–12 month contract.We are hiring a Senior Backend Engineer to lead the evolution of a global platform supporting international expansion and acquisition integration.This role focuses on building and scaling transaction systems that enable global commerce, while evolving an existing real-time platform to support new markets. You will address backend capacity constraints and help design a shared transaction and ledger layer used across multiple business lines.This is a hands-on senior engineering role requiring both high-quality delivery and strong technical leadership in ambiguous, high-scale environments.You will be expected to:Design scalable systems with correctness and failure modes considered from the outsetClarify and scope requirements before proposing solutionsMake pragmatic trade-offs in system design, avoiding over-engineeringOperate independently without reliance on AI tooling for core problem solvingFully understand, explain, and defend all systems and code you produceRoleThe Backend Engineer will be responsible for designing and scaling systems supporting multi-currency, cross-border transactionsBuilding and extending a shared transaction and ledger layerSupporting integration of newly acquired platform capabilitiesDesigning APIs for frontend, mobile, and seller platform use cases (REST and GraphQL)Handling complex transaction logic including:Currency conversionFees and commissionsReconciliationRefunds and adjustmentsSupporting region-specific requirements such as tax, shipping, and complianceImproving performance and scalability of real-time transaction systemsIdentifying bottlenecks and evolving platform architecture as demand growsProfileYou will operate within a modern distributed systems environment spanning multiple services, languages, and architectural patterns. The role combines hands-on ownership of backend services with architectural leadership responsibilities.Elixir and the Phoenix frameworkGraphQLPostgreSQLRedisWebSockets and Phoenix Channels for real-time communicationMessage-driven architectures and asynchronous processing patternsCloud-native infrastructure supporting globally distributed workloadsYou may interact with services and systems built in:PythonGoJavaKotlinC#TypeScript / Node.jsRubyRustAPI DesignYou will design, build, and consume:RESTful APIsGraphQL APIsCompanyUK's market leading media organisation with offices in LondonHybrid workingSalary & BenefitsThe salary range/rates of pay is dependent upon your experience, qualifications or training.