Senior Software Engineer - SecEng

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:

• 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

Who you are

• 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 have

• 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

Tech Stack

Klaviyo’s platform is primarily built with Python and React and runs on AWS. Engineers join us from a wide range of technical backgrounds and are supported in learning our stack. Core technologies include:

• Python / Django / Golang / FastAPI

• MySQL / Redis / Memcached

• RabbitMQ / Celery / Apache Kafka / Apache Pulsar

• AWS / Terraform / Kubernetes

Location & Work Model

This role is based in Boston, Massachusetts and follows a hybrid working model. Klaviyo supports work authorization and relocation for this position.

At Klaviyo, we enjoy tackling meaningful engineering challenges and value people who take ownership, learn continuously, and collaborate openly. We are committed to building inclusive teams and encourage applications from candidates of all backgrounds.

Klaviyo is growing fast and we have openings for all skill levels across all of our teams. Learn more about our engineering culture at https://klaviyo.tech

Massachusetts Applicants:
It is unlawful in Massachusetts to require or administer a lie detector test as a condition of employment or continued employment. An employer who violates this law shall be subject to criminal penalties and civil liability.

Our salary range reflects the cost of labor across various U.S. geographic markets. The range displayed below reflects the minimum and maximum target salaries for the position across all our US locations. The base salary offered for this position is determined by several factors, including the applicant’s job-related skills, relevant experience, education or training, and work location.

In addition to base salary, our total compensation package may include participation in the company’s annual cash bonus plan, variable compensation (OTE) for sales and customer success roles, equity, sign-on payments, and a comprehensive range of health, welfare, and wellbeing benefits based on eligibility.

Your recruiter can provide more details about the specific salary/OTE range for your preferred location during the hiring process.

Base Pay Range For US Locations:
$148,000—$222,000 USD

Get to Know Klaviyo

We’re Klaviyo (pronounced clay-vee-oh). We empower creators to own their destiny by making first-party data accessible and actionable like never before. We see limitless potential for the technology we’re developing to nurture personalized experiences in ecommerce and beyond. To reach our goals, we need our own crew of remarkable creators—ambitious and collaborative teammates who stay focused on our north star: delighting our customers. If you’re ready to do the best work of your career, where you’ll be welcomed as your whole self from day one and supported with generous benefits, we hope you’ll join us.

AI fluency at Klaviyo includes responsible use of AI (including privacy, security, bias awareness, and human-in-the-loop). We provide accommodations as needed.

By participating in Klaviyo’s interview process, you acknowledge that you have read, understood, and will adhere to our Guidelines for using AI in the Klaviyo interview Process. For more information about how we process your personal data, see our Job Applicant Privacy Notice.

Klaviyo is committed to a policy of equal opportunity and non-discrimination. We do not discriminate on the basis of race, ethnicity, citizenship, national origin, color, religion or religious creed, age, sex (including pregnancy), gender identity, sexual orientation, physical or mental disability, veteran or active military status, marital status, criminal record, genetics, retaliation, sexual harassment or any other characteristic protected by applicable law.

IMPORTANT NOTICE: Our company takes the security and privacy of job applicants very seriously. We will never ask for payment, bank details, or personal financial information as part of the application process. All our legitimate job postings can be found on our official career site. Please be cautious of job offers that come from non-company email addresses (@klaviyo.com), instant messaging platforms, or unsolicited calls.

By clicking "Submit Application" you consent to Klaviyo processing your Personal Data in accordance with our Job Applicant Privacy Notice. If you do not wish for Klaviyo to process your Personal Data, please do not submit an application. You can find our Job Applicant Privacy Notice here and here (FR).