Senior Staff Software Engineer

Senior Staff Software Engineer –.NET |C# |AWSElan Partners is seeking a Senior Staff Software Engineer with deep .NET/C# expertise to design and help drive the backend architecture of a large-scale, consumer-facing commerce platform processing billions of dollars in annual transactions. This is a highly technical, hands-on engineering role for someone operating between the Senior and Principal level, with near-architect-level system design capabilities. The ideal candidate has experience building high-volume, customer-facing transactional systems from the ground up and understands what it takes to design systems for scale, reliability, performance, and security. The environment is cloud-native and AWS-based, with a core backend stack of.NET and C#. Experience with e-commerce, payments, PCI-regulated platforms, ordering, fulfillment, or other high-throughput transactional environments is strongly preferred.Required QualificationsAdvanced hands-on development experience with.NET and C#Strong system design and distributed systems architecture experienceExperience designing and scaling microservices-based, cloud-native applicationsDeep experience with AWS, including services such as ECS/EKS, RDS, SQS, and related cloud infrastructureExperience building or playing a significant role in building a high-volume, customer-facing transactional platform from the ground upExperience designing systems where scalability, availability, latency, data integrity, and fault tolerance are criticalExperience supporting highly available, production-critical applicationsStrong understanding of observability, monitoring, incident response, and long-term system resilienceAbility to identify and resolve performance bottlenecks, scaling challenges, and architectural risksStrong technical leadership skills with the ability to establish engineering standards and mentor other engineersExcellent communication skillsPreferred QualificationsExperience within e-commerce, payments, PCI-DSS, ordering, fulfillment, or other high-volume transactional environmentsExperience building multiple large-scale transactional platforms or participating in multiple significant ground-up implementationsExperience designing systems for PCI-DSS compliance, secure data handling, and fraud-prevention considerationsExperience establishing backend architecture patterns and engineering best practices across development teamsThoughtful, practical use of AI-assisted engineering tools, such as Claude or similar development-focused tools, while maintaining strong engineering fundamentals and technical judgmentResponsibilitiesDesign and own distributed backend systems using.NET/C# within a cloud-native AWS environmentBuild and scale microservices supporting high-throughput transactional workloadsLead system design and architectural decisions impacting performance, scalability, reliability, and securityEnsure mission-critical services meet demanding requirements for availability, latency, fault tolerance, and data integrityDesign and maintain secure systems supporting PCI-DSS and transactional processing requirementsDrive improvements in system observability, monitoring, incident response, and production healthIdentify and resolve system bottlenecks, architectural risks, and scaling challengesDefine backend engineering standards, architectural patterns, and development best practicesPartner with product and business stakeholders to translate complex requirements into scalable technical solutionsMentor engineers and help elevate technical capability across the engineering organization