- 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 advancement
- Sezzle 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 transformation
- In this backend focused role, you will work closely with stakeholders from Product, Security, Support and the business
- You’ll also partner with engineering teams across the organization to deliver auth capabilities that are safe, incremental to adopt, and invisible to customers
- Your day-to-day responsibilities will include designing, developing, and delivering gateway and identity services,



as well as unblocking and mentoring your teammates
- Your work will generally focus on foundational platform capabilities, security-critical paths, and performance at the edge
- At 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 systems
- Own the technical vision and roadmap for Sezzle’s authentication and authorization platform, including a dedicated API auth gateway and supporting identity services
- Architect, design, and build scalable, highly-available auth services and gateway components primarily in Golang, leveraging AWS, RDS (MySQL/Postgres), and modern distributed patterns
- Design and lead phased, zero-downtime migrations of auth traffic and functionality, with clear rollback and sa

📌 Principal Software Engineer (Madrid)
🏢 Sezzle
📍 Madrid