Lead Software Engineer - Human User Access Team

At Klaviyo, we value the unique backgrounds, experiences and perspectives each Klaviyo (we call ourselves Klaviyos) brings to our workplace each and every day. We believe everyone deserves a fair shot at success and appreciate the experiences each person brings beyond the traditional job requirements. If you’re a close but not exact match with the description, we hope you’ll still consider applying. Want to learn more about life at Klaviyo? Visit careers.klaviyo.com to see how we empower creators to own their own destiny.

About the Team

The Human User Access (HUA) team is responsible for the core systems that ensure secure and seamless user authentication and authorization across our platform. We design and maintain access control mechanisms, including role-based and custom roles, to provide flexible yet robust user management. In addition to authentication services, we build and support internal tooling that empowers other teams, enhancing overall productivity and security. Our focus is on scalability, security, and user experience, ensuring our systems can meet the demands of a growing, global user base.

How You’ll Make a Difference

• Shape the Future of CIAM: Contribute to key projects in authentication, authorization, and access control, while driving the shift from a monolithic system to a scalable, service-oriented architecture.
• Own the Technical Vision: Lead the team in defining and executing the technical roadmap, aligning with strategic business goals and enabling long-term growth and innovation.
• Collaborate and Influence: Work closely with cross-functional teams to ensure our technical solutions support evolving product needs, directly impacting the user experience at scale.
• Drive Innovation: Implement architectural improvements that boost performance, scalability, and security, while ensuring adherence to industry best practices in code quality and infrastructure.
• Lead with Impact: Be a key player in delivering mission-critical services, including on-call support, ensuring system reliability and prompt resolution of issues in a high-traffic environment. Champion industry best practices in code quality, infrastructure, and processes, ensuring the delivery of secure, efficient, and reliable solutions.

Tech Stack

• Python, Go, Django, GRPC
• MySQL, PostgreSQL, Redis, Memcache
• Apache Kafka, Apache Pulsar, RabbitMQ, Spark, Airflow, and other tech from the big data stack
• Typescript, React, Babel, Jest, Webpack
• AWS, Terraform, Docker, Kubernetes, Pantsbuild, BuildKite

Who You Are

• Proven expertise in building access control systems.
• Passionate about solving complex problems, with a strong ability to diagnose performance, scalability, and reliability issues, and implement breakthrough solutions.
• Extensive experience designing and driving system architecture decisions, balancing trade-offs between performance, scalability, security, and maintainability.
• A strong advocate for industry best practices, especially around security and protecting sensitive data in systems handling user privacy and data integrity.
• Strong leadership and mentorship skills, with a commitment to guiding and developing engineers at various levels.
• Excellent communication skills, with the ability to effectively convey technical concepts to both technical and non-technical stakeholders.
• Expertise in DevOps practices and tooling (CI/CD, containerization, orchestration), ensuring smooth integration, delivery, and maintenance of services in production environments.
• Experience in balancing immediate priorities with long-term goals, ensuring that tactical tasks align with strategic objectives while managing technical debt effectively.
• Bachelor’s degree or equivalent practical experience, with 10 years of experience in developing and launching complex software products, and 5 years of hands-on experience in software design and system architecture, focused on reliability and high performance.

Nice to Have

• Experience with microservices architecture and the transition from monolithic systems.
• Familiarity with identity management protocols such as OAuth, OpenID Connect, and SAML.
• Experience working in cloud environments (AWS, GCP, Azure) and leveraging cloud-native services.
• Hands-on experience with infrastructure-as-code (Terraform, CloudFormation) and container orchestration (Kubernetes, Docker).
• Knowledge of modern programming languages like Go or Rust
• Experience working with data privacy regulations (GDPR, CCPA) and ensuring compliance in software systems.
• Background