Senior Back End Developer

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 environment
• Designing and scaling systems to support multi-currency and cross-border transactions
• Building and extending a shared transaction and ledger layer used across multiple platforms
• Supporting the integration of newly acquired products and capabilities into the core platform
• Designing and exposing APIs for frontend, mobile, and third-party platform use cases
• Handling complex transaction logic including currency conversion, fees, reconciliation, and refunds
• Supporting region-specific requirements such as tax, compliance, and shipping logic
• Improving performance, resilience, and scalability of transaction-heavy systems
• Leading architectural decisions across backend and platform services
• Mentoring engineers and contributing to higher backend engineering standards
• Collaborating closely with frontend, mobile, and product teams to deliver global user experiences

Skills:

• Extensive experience working as a Senior Backend Engineer in production environments
• Strong background designing and building distributed systems and APIs
• Proven experience building or scaling payment, ledger, or transaction systems
• Experience working with Elixir and GraphQL (strongly preferred)
• Background in eCommerce or transaction-heavy, real-time platforms operating across regions
• Ability to evolve existing systems pragmatically in fast-moving environments
• Comfortable operating with ambiguity and a strong sense of ownership
• Strong communication skills and experience working within cross-functional teams

Contract:

• Initial 6-month contract with potential to extend
• Inside IR35
• London-based assignment with hybrid working (on-site expectation)

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