Software Engineer II

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  to see how we empower creators to own their own destiny.

Klaviyo is a world-leading marketing automation platform dedicated to accelerating revenue and customer connection for online businesses using the channels they own like email, web and mobile. Enabling brands to leverage these owned marketing channels, Klaviyo makes it easy to store, access, analyze and use transactional and behavioral data to power highly-targeted customer and prospect communications. The company’s hybrid customer-data and marketing-platform model allows companies to grow by fostering direct, high-fidelity relationships with customers, without giving up their valuable data to Facebook or Amazon.

In 2020, Klaviyo reached coveted unicorn status with a robust Series C of $200m at $4.15B valuation. Innovative companies like Unilever, Custom Ink, and Huckberry sell more with Klaviyo.

The Product Expansion / Activation team at Klaviyo is focused on improving the early experience of Klaviyo for new customers. We work diligently to improve the rate at which customers are successfully setting up their Klaviyo account and gaining value from the platform. Engineers on the team use data to discover opportunities for improvement, implement A/B tests to validate ideas, and work across the product to iteratively improve UX and reduce friction for new customers.

We are looking for great generalist software engineers with a passion for the experience-layer that have an interest in or experience with growing a user‑base and building a great customer onboarding pipeline and experience.

• Implement user-experience improvements across the Klaviyo product, especially in areas that affect new customers.
• Design and implement A/B tests to validate ideas, and interpret the results of these tests to inform iterative improvements to the product.
• Collaborate with marketing, data science, sales, and engineering teams to discover areas for improvement, as well as engaging with customers directly to learn more about how we can better serve their needs.
• Help improve our experimentation and development processes, and mentor other engineers on the team.
• Clearly define the goal, constraints, and context for AI agents, while remaining responsible for the correctness of the implementation, with a focus on security, performance, and maintainability.
• Work from our Boston HQ at least three days a week.

• Have a background in full stack software engineering with experience building and improving products with an emphasis on user‑facing features, along with the APIs and infrastructure to support them.
• Passionate about growing and improving a product on a daily basis using a data driven mindset.
• Experienced with A/B testing products with metric based goals to improve user experience and customer acquisition and success (nice to have).
• Demonstrated ability and success in using AI-driven software delivery practices and methods and/or a willingness and excitement to learn.
• Thrives in an entrepreneurial type environment that is fast paced, customer focused, and strategic.

• Python, Django
• Amazon Web Services (EC2, RDS, Aurora, etc.), Terraform, Ansible, Packer, and other Dev Ops tools

Base Pay Range for US Locations: $116,000 — $174,000 USD

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.

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.