Robert Half have partnered with a high growth sports manufacturing organisation based in London who are looking to engage an experienced Senior Backend Engineer to support the evolution of a live, transaction-driven platform as it scales internationally.This is an initial 6-month, Inside IR35 contract, focused on building and scaling core backend systems that support global commerce, real-time interactions, and the integration of newly acquired platform capabilities.Responsibilities:Owning and evolving backend services within a high-scale, real-time environmentDesigning and scaling systems to support multi-currency and cross-border transactionsBuilding and extending a shared transaction and ledger layer used across multiple platformsSupporting the integration of newly acquired products and capabilities into the core platformDesigning and exposing APIs for frontend, mobile, and third-party platform use casesHandling complex transaction logic including currency conversion, fees, reconciliation, and refundsSupporting region-specific requirements such as tax, compliance, and shipping logicImproving performance, resilience, and scalability of transaction-heavy systemsLeading architectural decisions across backend and platform servicesMentoring engineers and contributing to higher backend engineering standardsCollaborating closely with frontend, mobile, and product teams to deliver global user experiencesSkills:Extensive experience working as a Senior Backend Engineer in production environmentsStrong background designing and building distributed systems and APIsProven experience building or scaling payment, ledger, or transaction systemsExperience working with Elixir and GraphQL (strongly preferred)Background in eCommerce or transaction-heavy, real-time platforms operating across regionsAbility to evolve existing systems pragmatically in fast-moving environmentsComfortable operating with ambiguity and a strong sense of ownershipStrong communication skills and experience working within cross-functional teamsContract:Initial 6-month contract with potential to extendInside IR35London-based assignment with hybrid working (on-site expectation)Robert Half Ltd acts as an employment business for temporary positions and an employment agency for permanent positions. Robert Half is committed to diversity, equity and inclusion. Suitable candidates with equivalent qualifications and more or less experience can apply. Rates of pay and salary ranges are dependent upon your experience, qualifications and training. If you wish to apply, please read our Privacy Notice describing how we may process, disclose and store your personal data: