We are seeking a talented and motivated best-in-class Principal Software Engineer to own and lead the evolution of authentication and authorization at Sezzle. This role presents an exciting opportunity to thrive in a dynamic, fast-paced environment within a rapidly growing team, with abundant prospects for career advancementSezzle is investing in the next generation of its authentication and authorization platform, centered on a purpose-built API auth gateway and a clean set of identity and access management services. As the Principal Software Engineer leading this effort, you will own the technical vision, architecture, and migration strategy for this transformationIn this backend focused role, you will work closely with stakeholders from Product, Security, Support and the businessYou’ll also partner with engineering teams across the organization to deliver auth capabilities that are safe, incremental to adopt, and invisible to customersYour day-to-day responsibilities will include designing, developing, and delivering gateway and identity services,



as well as unblocking and mentoring your teammatesYour work will generally focus on foundational platform capabilities, security-critical paths, and performance at the edgeAt Sezzle, AI-assisted development is a standard part of how we build, paired with the rigorous review and security discipline the auth-critical path demands. As a principal engineer, you will help set the pattern for how AI tooling is used well on security-sensitive systemsOwn the technical vision and roadmap for Sezzle’s authentication and authorization platform, including a dedicated API auth gateway and supporting identity servicesArchitect, design, and build scalable, highly-available auth services and gateway components primarily in Golang, leveraging AWS, RDS (MySQL/Postgres), and modern distributed patternsDesign and lead phased, zero-downtime migrations of auth traffic and functionality, with clear rollback and safety mechanisms at every step

📌 Principal Software Engineer (Madrid)
🏢 Sezzle
📍 Madrid