Senior Payments Engineer — Acquiring & Payment Processing

About this job

Sezzle is on a mission to financially empower the next generation through innovative, interest-free installment plans that enhance the shopping experience and drive merchant sales. The company operates in a dynamic fintech environment, blending advanced technology with a commitment to seamless transactions. As a Senior Payments Engineer for Acquiring & Payment Processing, you will take ownership of the core backend services that integrate with major payment processors and gateways. Your team builds resilient, auditable systems that manage complex money-movement flows. A normal day in this role involves designing and building robust backend services in Golang, monitoring transaction health and performance metrics, and collaborating closely with product, risk, compliance, and support teams. You will also utilize AI tooling like Claude to accelerate your daily workflow for design, coding, testing, and documentation, while mentoring peers and driving scalable solutions to intricate authorization, settlement, and reconciliation challenges.

Responsibilities

• Design and build backend services in Golang to integrate with payment processors, gateways, and card networks.
• Manage critical money-movement flows end-to-end, covering authorization, capture, settlement, refunds, reconciliation, and disputes.
• Develop idempotent, fault-tolerant, and auditable transaction processing within distributed architectures.
• Operate within PCI DSS scope, ensuring secure handling of payment data, tokenization, and 3DS/SCA flows.
• Monitor payment health indicators including authorization rates, latency, and settlement accuracy for continuous improvement.
• Leverage AI tooling such as Claude within company security policies to accelerate design, research, coding, and testing.
• Mentor engineering teammates and help elevate technical standards across the group.

Requirements

• 7+ years of backend or full-stack engineering experience focused on payments, fintech, or money-movement systems.
• Strong proficiency in Go, or comparable experience in Python building and serving REST APIs.
• Hands-on background integrating with payment processors, gateways, or acquiring systems.
• Familiarity with payments fundamentals such as authorization versus settlement, tokenization, and chargebacks.
• Experience working in distributed, cloud-based architectures using transactional outboxes or queuing tools like Kafka, SQS, or RabbitMQ.
• Demonstrated hands-on use of Claude or equivalent LLMs to enhance productivity and communication.
• Bachelor's degree in Computer Science, Engineering, or a related field.

Good to have

• Direct experience with the payments acquiring ecosystem including Adyen, Stripe, Marqeta, or Fiserv.
• Exposure to PCI DSS, 3DS/SCA, network tokenization, or payments compliance.
• Experience with SQL-based RDBMS through an ORM tool.
• Familiarity with observability platforms like Prometheus, Datadog, or New Relic.
• DevOps experience with CI/CD pipelines and containerized microservices on Kubernetes and AWS.

Who should apply

This role suits experienced backend engineers with a strong background in fintech, payments, and money-movement systems who thrive in high-ownership environments. Ideal candidates possess a deep understanding of distributed architectures and demonstrate a strong commitment to secure-by-default engineering. Because Sezzle runs an AI-first culture, applicants must be comfortable integrating AI tools like Claude into their daily development workflows. Freshers should not apply, as the position specifically requires 7+ years of relevant engineering experience.

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