Software Engineer II

About the Role

Klaviyo is looking for a Full Stack Engineer to support key initiatives that enhance our product offerings and drive company growth. In this role, you'll play a critical part in delivering end-to-end solutions using both front-end and back-end technologies. You’ll improve existing products and develop new capabilities that push the boundaries of what’s possible for our customers.

As a Software Engineer II, you’ll tackle complex challenges, explore multiple solutions, and weigh business and technical trade-offs to determine the best path forward. You’ll actively contribute to team discussions and help shape important technology decisions. You'll also be responsible for shipping well-designed, thoroughly tested solutions that prioritize reliability and performance.

The Whats App team builds the end-to-end experience for Klaviyo’s Whats App channel, making it easy and powerful for customers to use our newest messaging channel effectively. We own the core Whats App product surface across Klaviyo, ensuring it’s available wherever customers expect it, while building and operating Whats App-specific capabilities like outbound and inbound pipelines and Meta template management.

We work cross-functionally by default. Partnering closely with teams across the org gives us broad exposure to the product, lets us unblock other teams, and allows us to drive impact well beyond our immediate scope. The work is fast-moving, varied, and forces us to constantly learn and adapt.

Looking ahead, our focus is on scaling Whats App across Klaviyo. That means closing feature gaps, rapidly integrating new Meta capabilities, and running targeted adoption experiments to drive usage. The goal is simple: deliver the most complete, high-quality Whats App integration in the market—and set the bar for what a marketing platform can do with this channel

• A proven track record of building high-quality products and systems, with a focus on writing clean, maintainable code
• 3+ years of experience in a software engineering role
• Experience building end-to-end software solutions or deep experience with both front-end and back-end technologies
• Familiarity with code reviews and leading or participating in robust testing practices
• Experience working in agile, fast-paced environments

• Experience with Python and related technologies
• Experience with React and related technologies
• Background in digital marketing or customer data software
• Exposure to machine learning concepts or applications
• Experience building cloud-native solutions, ideally on AWS