Principal Software Engineer - Identity & Access Management

Job description

About this role

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.

Responsibilities

• - 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 safety mechanisms at every step.
• - Establish and evolve authentication and authorization standards across the platform: OAuth2/OIDC flows, token strategy (JWT, opaque, refresh), service-to-service auth (mTLS, workload identity), and fine-grained authorization models (RBAC/ABAC/policy engines).
• - Drive consistency and scalability across a distributed microservices architecture while maintaining the performance, reliability, and latency budgets expected of an edge gateway.
• - Partner with Security and Compliance to ensure the new platform meets fintech-grade security and regulatory requirements , and champion secure-by-default patterns across engineering.
• - Establish and evolve engineering best practices for observability, security, and CI/CD across teams, with particular rigor on the auth-critical path.
• - Participate in the on-call rotation for the services you own, and help lead incident response and postmortems on the auth-critical path.
• - 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.

Qualifications and requirements

• - 12+ years of professional software engineering experience, including significant backend experience.
• - Deployed significant changes to a production application in the past 30 days.
• - Experience designing, building, or operating an API gateway or auth proxy at scale : whether a commercial/open-source gateway (e.g., Kong, Envoy, AWS API Gateway, Traefik) or an in-house edge service.
• - Strong proficiency in Golang , with experience building and maintaining RESTful APIs .
• - 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, queues) and the specific challenges of high-throughput, low-latency edge services.
• - Demonstrated ability to bring new ideas forward , influence decisions, and lead complex technical initiatives across many teams.
• - Bachelor’s degree in Computer Science or a similar technical field (required).