Senior Software Engineer - SecEng

Klaviyo•Boston, MA

8h•Hybrid

About The Position

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 klaviyo.com/careers to see how we empower creators to own their own destiny. Team Overview The Infrastructure Security team makes it simple and easy for engineers to make secure choices while developing world-class software at high speed. Security is built in by default—seamless and effortless—making engineers’ lives better and Klaviyo more secure. Our work sits at the intersection of security, infrastructure, and software engineering. We build cloud-native platforms and services that are reliable, secure, and performant at global scale, forming the foundation that Klaviyo engineers rely on every day. This role is for engineers who enjoy building modern distributed systems, care about security and reliability, and want to have real impact across a large engineering organization. How you’ll make an impact As a Senior Software Engineer on the Infrastructure Security team, you will build and operate the systems that help Klaviyo engineers ship secure software with confidence. You will:

Requirements

You have 6+ years of solid experience building and operating cloud-native, distributed systems in production
You are comfortable writing production-quality code in a language such as Python or Go
You have hands-on experience with AWS (or a similar cloud provider) and understand managed services, networking, and IAM concepts
You have experience working with containers and orchestration platforms such as Kubernetes
You are comfortable owning services and features independently, while knowing when to ask for feedback or support
You understand the fundamentals of scalable, multi-tenant architectures and secure system design
You care about reliability, performance, observability, and security—not just shipping features
You are comfortable participating in on-call and responding to production issues
You are an excellent communicator and collaborator. You lead technical discussions at the project and product-area level, write clear technical design documents and RFCs, and keep stakeholders aligned on progress, risks, and trade-offs.
Ability to handle yourself and complex systems in outage situations and to drive failures to root cause analysis and prevention of future issues.
You’ve already experimented with AI in work or personal projects, and you’re excited to dive in and learn fast. You’re hungry to responsibly explore new AI tools and workflows, finding ways to make your work smarter and more efficient.
You question convention and proactively look for ways to improve, whether that’s workflows, architecture, tooling, or team processes. You are intrinsically motivated to drive incremental and step-change improvements that deliver value to the business.
You mentor and support other engineers, offering thoughtful feedback in design and code reviews, helping refine specifications, and investing in the growth of more junior engineers on the team.
You enjoy working on small, autonomous, agile teams, shipping early and often, pairing with product managers, business stakeholders, and other engineers to craft better software.

Nice To Haves

Experience building security tooling, working with security infrastructure systems like Vault, AWS IAM, WAFs, and more
Experience with service meshes, API gateways, or zero-trust architectures
Experience improving performance in distributed systems or debugging complex multi-service workflows

Responsibilities

Design, build, and maintain cloud-native security services used across Klaviyo
Own meaningful components and services end to end, from implementation through production operation
Improve the availability, scalability, latency, and efficiency of infrastructure security systems
Collaborate with senior engineers on system design and architecture, contributing ideas and technical solutions
Identify performance, reliability, and security issues in distributed systems and drive improvements
Work extensively with technologies such as Python, Golang, AWS, Kubernetes, Terraform, and modern data stores
Participate actively in design reviews, code reviews, and whiteboarding sessions
Contribute to operational excellence through monitoring, alerting, and incident response
Participate in an on-call rotation with a focus on learning, prevention, and reducing operational toil
Build tooling, automation, and documentation that improve developer experience and security posture
Partner with product-facing and platform engineers to ship impactful, secure solutions