Senior Software Engineer

About the role

At Klaviyo, we value the unique backgrounds, experiences and perspectives each Klaviyo, which we call Klaviyos, brings to our workplace every day. We believe everyone deserves a fair shot at success and appreciate the experiences each person brings beyond traditional job requirements. If you are a close but not exact match with the description, we still encourage you to consider applying. To learn more about life at Klaviyo, you can visit klaviyo.com/careers to see how we empower creators to own their own destiny.

The PLS team is responsible for building and scaling the core customer data experiences at Klaviyo, specifically Profiles, Lists, and Segments. We own the tools that allow customers to understand who their users are, group them into meaningful audiences, and keep those audiences up to date as new data flows in. Our work directly underpins how customers target, personalize, and measure every message they send, making this product area central to Klaviyo's continued success. As a Senior Software Engineer on this team, you will play a key role in designing and building scalable systems that power how customers manage and activate their data. You will partner closely with product managers, data scientists, and other platform teams to help define scope, translate complex data and UX problems into practical implementations, and build intuitive workflows that give customers confidence in their audiences. This role leans frontend, with a strong focus on crafting thoughtful, reusable components and seamless user experiences using technologies such as TypeScript, React, Python, and Django. Given the scope of this role and the team's central role in Klaviyo's product, there are ample opportunities for growth.

What you'll do

You will be a core member of the PLS team, working on impactful customer-facing features that will make our product the best in the industry. You will work on creating easy-to-use editors that are highly performant and build systems that let customers understand who their users are and group them into meaningful audiences. You will work closely with Product, Design, and Data Science to provide the best experience for our customers and mentor team members to drive initiatives that help the team learn new skills. This role leans frontend, with a strong focus on crafting thoughtful, reusable components and seamless user experiences.

You will define scope and translate complex data and UX problems into practical implementations for customer data management. You will build intuitive workflows and easy-to-use editors that are highly performant for managing profiles, lists, and real-time segments. You will leverage React, TypeScript, Redux, and Python to craft thoughtful, reusable components and seamless user experiences. You will partner closely with product managers, data scientists, and platform teams to align on requirements and drive project execution. You will mentor team members and lead initiatives that help the team learn new skills and improve quality. You will conduct code reviews and run a robust testing cycle using automated testing practices and frameworks, including end-to-end and integration tests such as Cypress and pytest. You will evolve APIs and data models using RESTful and GraphQL approaches to support product success and scalability. You will own your work from requirements and edge cases through implementation and testing to solve tough problems collaboratively. You will lead complex, multi-quarter projects involving cross-team collaboration and be accountable for outcomes and delivery. You will contribute to the core tools that let customers understand, group, and activate their audiences as data flows in. You will drive frontend innovation to ensure customers gain confidence in their audiences and the accuracy of their data. You will support the central product area that underpins how customers target, personalize, and measure every message they send. You will collaborate on design systems and component libraries to maintain consistency and performance across the product. You will help define and improve the developer experience around data workflows to enable faster experimentation and iteration.

Requirements

You have 5+ years of experience in full-stack development with strong hands-on skills in React, Redux, JavaScript, HTML, and CSS. You have a track record of delivering and shipping work powered by or accelerated through AI. You have experience conducting code reviews and running a robust testing cycle using automated testing practices and frameworks, including end-to-end and integration tests such as Cypress and pytest. You are experienced with RESTful and GraphQL APIs, and evolving APIs and data models to support product success. You take ownership of your work - from requirements and edge cases to implementation and testing - and are motivated by solving tough problems with others. You have a proven track record of leading complex, multi-quarter projects involving cross-team collaboration and being accountable for their outcomes. You are comfortable working in a fast-paced environment where priorities can shift and problems require creative solutions. You have strong written and verbal communication skills to collaborate effectively with cross-functional partners. You have the ability to mentor team members and contribute to a learning culture within the PLS organization.

Compensation and location

Location: USA

Engagement: Full-time

Practical notes

Only include hours, travel, visa, or deadlines stated in the source material.