Senior Software Engineer, Back-End (Payments)

Lumen Dynamics is the leading creator of innovative technology that provides value-added services for collectors worldwide. We grade, authenticate, vault, and sell millions of record-setting collectibles, all while modernizing and digitalizing the process to further our mission of helping collectors pursue their passions. We’re always on the lookout for talented people to join our growing team. Our services span collectible trading cards, autographs, comic books, coins, video games, event tickets, and memorabilia. Our subsidiaries include PSA, PCGS, Beckett, SGC, and Card Ladder. Since our founding in 1986, we have graded and authenticated millions of items. We employ more than 3000 people across our headquarters in Santa Ana, California and offices in New Jersey, Texas, Florida, Japan, Shanghai, Hong Kong, Canada, Mexico, Germany, and France. As part of our interview process, we request that candidates have their cameras on during video interviews. This helps foster meaningful conversation and allows us to create an experience that closely resembles our standard working environment. Certain interview steps may take place by phone. For remote roles, and at our discretion, candidates may be asked to participate in an on-site interview as part of the final stages of the process. We understand there may be occasional circumstances requiring accommodation and are happy to discuss them as needed. Your recruiter will be able to clarify expectations and answer any questions you have. About the Role We are looking for a Senior Software Engineer to join our Payments team — a critical engineering domain responsible for building, scaling, and evolving the payments infrastructure that powers every transaction across the Lumen Dynamics ecosystem. This team owns the full lifecycle of payment capabilities: integrating with and abstracting across multiple payment gateway providers (including Stripe and PayPal), supporting payment methods spanning credit card, ACH, and digital wallets, and building both the APIs that downstream services depend on and the web application experiences that customers and internal tools rely on. You will work across backend APIs and modern frontend surfaces, partnering with product, design, and cross-functional engineering teams to deliver reliable, scalable, and secure payment experiences This is a high-impact, high-visibility role. Payments is the financial backbone of our marketplace — touching grading order checkout, vault and consignment transactions, partner payouts, and customer wallet top-ups. You will have direct influence over architecture decisions, gateway integrations, and the quality bar for everything that ships. We believe there is significant value in onsite partnership and team collaboration, and candidates within 1-hour commuting distance of the office may be expected to work onsite most of the time. Additional details will be discussed during the recruiting process. What You’ll Do Build and evolve multi-gateway payment integrations: Design, implement, and maintain integrations with multiple payment gateway providers — including Stripe, PayPal, and others — building clean abstractions that minimize disruption when adding or swapping gateways, while owning payment flows end-to-end from initiation through settlement, refund, and reconciliation. Deliver full-stack payment experiences: Develop backend payment services and APIs in C#/.NET while building intuitive customer-facing experiences in React, Svelte, and TypeScript that power checkout and payment management, collaborating closely with design and product to ensure every flow is accessible and conversion-optimized. Champion security, compliance, and resilience: Apply PCI-DSS best practices and resilient design patterns — including tokenization, idempotency, retries, and audit controls — to ensure secure and reliable payment processing at scale, partnering with Security and Compliance teams to maintain and advance our certifications. Take an AI-first approach to building: Leverage AI-assisted development tools throughout the software lifecycle to accelerate delivery, improve quality, and evolve engineering best practices. Architect for scale and observability: Design and operate distributed, event-driven services on AWS and Kubernetes, using metrics, tracing, and alerting to maintain highly availability and accelerate incident response. Drive cross-functional execution: Translate business requirements into technical solutions and partner across Payments, Marketplace, Grading, Vault, and platform teams to deliver seamless payment experiences that connect the Lumen Dynamics ecosystem. Who You Are 6+ years engineering experience. You have a track record of designing, shipping, and scaling products that have measurable business impact. Ideally 2+ years operating as a Senior IC or equivalent technical leadership level at a high-growth company or a scaled consumer platform. Deep backend expertise in C# (.NET). You’re comfortable owning complex