Principal Engineer - Infrastructure

Sezzle is a fintech company focused on revolutionizing the shopping experience through innovative payment solutions. They are seeking a Principal Engineer with a focus on Infrastructure to architect and build scalable infrastructure solutions, drive team roadmaps, and enhance reliability and developer productivity through AI and automation.

Responsibilities:

• Architect, upgrade, design, and build scalable infrastructure solutions leveraging Kubernetes, AWS, RDS (MySQL/Postgres), and modern distributed patterns
• Help drive the infrastructure and engineering teams’ roadmaps, leading us to higher levels of reliability, recoverability, and scalability
• Find and fix issues across our systems before they become issues in production, through tooling, alerts, AI, collaboration with teams, whatever it takes
• Drive capacity planning, benchmarking, and work with the team to stress test our systems, find bottlenecks, and prepare for further growth in the business
• Define, maintain and enforce SLAs and alerts across our infrastructure
• Help Lead Sezzle’s AI enablement efforts, identifying opportunities to apply AI and automation to enhance infrastructure reliability, developer productivity, and internal tooling
• Build in consistency and scalability across a distributed microservices architecture while maintaining performance and reliability
• Establish and evolve engineering best practices for observability, security, and CI/CD across teams
• Mentor engineers and champion a culture of learning, innovation, and operational excellence
• Collaborate cross-functionally to translate business goals into technical roadmaps and deliver results that matter

Requirements:

• 15+ years of professional software engineering or infrastructure engineering experience, including significant backend development and production engineering experience
• Deployed significant changes to a production application or infrastructure configuration in the past 30 days
• Strong proficiency in Golang, with experience building and maintaining RESTful APIs
• Deep expertise with SQL-based RDBMS (MySQL, PostgreSQL) and experience optimizing schema and queries for performance at scale
• Solid understanding of distributed systems design patterns (e.g., transactional outbox, event-driven architecture and stream processing, queues)
• Demonstrated ability to bring new ideas forward, influence decisions, and lead complex technical initiatives
• Bachelor's degree in Computer Science or equivalent practical experience
• Familiarity with AI developer tooling like Claude Code, Gemini CLI, Codex, Cursor and using it to be a more productive engineer
• Experience with AWS cloud infrastructure, mainly AWS Aurora RDS, both MySQL and Postgres
• Proficiency in observability tools (Prometheus, Grafana, Datadog, New Relic)
• Experience with data engineering, data pipelines and data warehousing
• Experience with CI/CD pipelines and deploying containerized microservices in Kubernetes
• Track record of shipping commercial APIs and data-driven applications in high-growth environments
• Proven leadership in guiding technical direction, improving system reliability, and scaling high-traffic services