Senior Payments Engineer — Acquiring & Payment Processing

The salary range for this role is $5,000 - $9,500 per month (Gross in USD) About Sezzle: With a mission to financially empower the next generation, Sezzle is revolutionizing the shopping experience beyond payments, blending cutting-edge tech with seamless, interest-free installment plans that make shopping smarter and more accessible. We’re not just transforming payments; we’re redefining how people discover, interact with, and purchase the things they love while driving real impact on merchant sales through increased conversions and higher order values. As we continue to shape the future of fintech and retail, we’re building an innovative, dynamic team passionate about creating more than just a transaction but a truly unique shopping journey. If you’re excited about pushing boundaries in tech and delivering a game-changing experience for consumers and merchants alike, come join us at Sezzle and help create the future of shopping! Compensation : For this senior development role, with 7+ years of experience, the compensation range is $5,000 - $9,500 USD per month. This range acknowledges the extensive expertise, leadership capabilities, and significant contributions expected at this level, offering a competitive salary to reflect the value of advanced skills and experience. About the Role: We're hiring a Senior Payments Engineer to own and scale the systems at the heart of Sezzle's acquiring and payment-processing stack — the services that integrate with processors and gateways (Stripe, Adyen, Fiserv, Plaid, and more partners from the broader acquiring ecosystem), move funds, and keep transactions accurate, auditable, and resilient. This is a backend-focused, high-ownership role. You'll partner closely with Product, Risk, Compliance, and Support, as well as other engineering teams, to deliver scalable solutions to hard problems in authorization, settlement, reconciliation, and disputes. You'll mentor teammates, unblock peers, and occasionally lead small project teams to delivery. What You'll Do: • Design and build backend services in Golang that integrate with payment processors, gateways, and card networks • Own critical money-movement flows end to end: authorization, capture, settlement, refunds, reconciliation, and chargeback/dispute handling • Build idempotent, fault-tolerant, auditable transaction processing within a distributed architecture (transactional outbox patterns; queues such as Kafka, SQS, or RabbitMQ) • Operate within PCI DSS scope — tokenization, network tokens, secure handling of payment data, and 3DS/SCA flows where applicable • Instrument and monitor payment health: authorization/decline rates, processor performance, latency, and settlement accuracy, driving continuous improvement • Use AI tooling (Claude and equivalent LLMs) as part of your daily workflow to accelerate design, coding, research, testing, and documentation — within Sezzle's security and data-handling policies • Mentor engineers and help raise the bar across the team • Demonstrated experience working with Claude or equivalent large language model tools is required; candidates must be comfortable leveraging AI to enhance productivity, research, and communication. What We Look For: • 7+ years of backend or full-stack engineering experience, with meaningful time spent on payments, fintech, or money-movement systems • Strong Go (preferred), or comparable experience in Python, building and serving REST APIs • Hands-on experience integrating with payment processors, gateways, or acquiring systems, and familiarity with payments fundamentals: authorization vs. settlement, tokenization, idempotency, reconciliation, and chargebacks/disputes • Experience in distributed, cloud-based architectures using patterns like transactional outboxes