Senior Software Engineer, Infrastructure Security

Requirements

• You care deeply about building software for the long term, balancing technical quality, delivery pace, and business impact.
• You have strong hands on experience with Linux operating systems and computer networking.
• You’re comfortable and experienced writing code in a programming language such as Python, Ruby, Go, etc.
• You have deep experience with cloud infrastructure, operating in a high scale environment.
• You have strong hands-on experience building and operating highly available systems, and are comfortable owning complex problems end to end.
• You’ve led the delivery of significant projects or features independently, including discovery, technical design, implementation, rollout, and ongoing maintenance, and you’re comfortable providing technical direction to others.
• You have deep expertise in one or more areas of modern web engineering (e.g. backend services, data pipelines, internal platforms, or AI-enabled systems) and a solid understanding of scalable, multi-tenant architectures.
• You regularly use AI-powered tools in your development workflow and are curious about applying AI thoughtfully to improve engineering productivity and system capabilities.
• You take ownership of operational excellence for the systems you build, including performance, reliability, observability, and on-call participation where required.
• You enjoy questioning convention and continuously improving how things work, whether that’s architecture, tooling, workflows, or team practices.
• You are a clear communicator and collaborative teammate, comfortable leading technical discussions, writing design docs or RFCs, and keeping stakeholders aligned.
• You enjoy working in small, autonomous, agile teams, shipping incrementally, and partnering closely with product managers and other engineers to deliver better outcomes.

What You'll Be Doing

• Ship foundational security services to enable Klaviyo engineering to move faster with confidence
• Design and develop systems and processes that enable highly available & scalable systems
• Design, build and deliver software to dramatically improve the availability, scalability, latency, and efficiency of Klaviyo’s services
• Achieve break-throughs in systems throughput by identifying and eliminating bottlenecks
• Leverage technology such as Python, Golang, AWS, Django, Kubernetes, Bash, Terraform, MySQL, Redis, Clickhouse, Iceberg, DataLake, Istio, Postgresql, and more to advance Klaviyo’s platform
• Champion best practices by actively collaborating with other teams in a culture that values whiteboarding and technical design review
• Contribute to the company as a subject matter expert in multiple areas, constantly pushing yourself to be a better engineer and to level up all of your peers within your team and within Klaviyo.
• Mentor and pair with other Klaviyo engineers to build better software by focusing on performance, self-healing system, configuration as code; defensive programming, application security, etc.
• Participate in periodic on call duties with a focus on solving issues when they are discovered, preventing recurrences and minimizing alert fatigue 
• Prototype and advocate for architectural improvements to achieve breakthrough results in Klaviyo systems’ operational scalability and reliability
• Work hand-in-hand with product-facing engineers to ship impactful code
• Perform quantitative investigation to understand and scale Klaviyo systems and manage the cross-functional effort to resolve scalability issues
• Produce and advocate for preventative, upstream solutions with internal stakeholders and external vendors and dependencies
• Confidently make informed, data-driven choices in a fast paced environment with competing priorities

Nice to Have

• Experience building security tooling, working with security infrastructure systems like Vault, AWS IAM, WAFs, and more
• Hands-on experience including diagnosing and improving systems performance, database queries, and complex, multi-service workflows.

Perks and Benefits

• This role may require up to 10% travel for purposes such as new hire onboarding, client or partner work if applicable, team meetings, and industry events. Travel is coordinated in advance.
• Hybrid working model based in Dublin, Ireland with support for work authorization and relocation.
• Generous benefits and a commitment to building inclusive teams.