Lead Software Engineer - Experimentation & Optimization

Location: Boston, MA

Klaviyo operates a real-time data analytics platform, built primarily in Python and hosted on Amazon Web Services (AWS), scalable by design to meet increasing demand. Engineers at Klaviyo bring experience from diverse backgrounds and disciplines, contributing to a collaborative and high-impact environment.

The Experimentation & Optimization team is a full-stack engineering team that builds intuitive and robust experimentation solutions for Klaviyo users. We prioritize rigorous statistical methods and ensure model explainability, working closely with data scientists and UX designers to create a seamless user experience. Our team is responsible for developing and enhancing Klaviyo’s experimentation platform, enabling users to experiment with and optimize campaigns, flows, and forms to improve audience engagement. By providing a powerful platform, expert guidance, in-depth analysis, and actionable insights, we help businesses extract meaningful learnings from their data. Our work integrates deeply with Klaviyo’s core technologies, requiring close collaboration across the engineering organization to build scalable, data-driven solutions.

As a Lead Software Engineer on the Experiments Platform Team, you will play a key role in shaping the architecture and strategy for experimentation at Klaviyo. You’ll lead technical discussions on how to design and implement robust experimentation features that help users optimize their marketing efforts. You’ll own the team’s mission, goals, and roadmap, collaborating closely with technical product owners and managers to develop a cohesive strategy that aligns both technical and business objectives. Your work will directly impact Klaviyo’s customers by enabling them to make data-driven decisions that enhance engagement and business outcomes.

Our tech stack includes 

• Python, FastAPI, gRPC, TypeScript, React, AWS, Django, and Spark.
• MySQL, PostgreSQL, Clickhouse, Redis, DynamoDB
• AWS, Terraform, Docker, Argo

How You Will Make a Difference

• Lead the technical vision for experimentation and optimization at Klaviyo, shaping how we design, build, and scale our experimentation platform.
• Deliver key product capabilities in experimentation and optimization, enabling users to test and refine campaigns, flows, and forms to maximize engagement.
• Work with large-scale data volumes to build systems that provide actionable insights to businesses of all sizes, from small startups to enterprise customers.
• Design and implement scalable experimentation infrastructure that processes massive datasets efficiently.
• Research, test, and productionalize experimentation methodologies and algorithms that provide measurable improvements in user engagement.
• Become a subject matter expert (SME) in experimentation and optimization, helping to drive best practices across the organization.
• Work cross-functionally with product, design, and data science teams to create a seamless experimentation experience for Klaviyo users.
• Have ample opportunities for growth and impact, given the scope of this role and the team’s central role in Klaviyo’s product strategy.

Who You Are

• 10+ years of experience as a hands-on software engineer.
• Experience architecting and building intuitive, consistent APIs in either REST or GraphQL
• Passionate about creating systems that elegantly simplify complex patterns and practices
• Proven ability to lead the technical vision for a platform or product area, shaping architecture and strategy to drive impact.
• Successfully led and delivered complex, multi-quarter projects involving multiple teams.
• Motivated to grow the team, both by mentoring team members and attracting new talent to expand our capabilities.
• Excited to dive into the code, deeply understand the experimentation and optimization space, and provide applicable technical mentorship.
• Strong understanding of cloud architectures and scalable systems, knowing the right tools to use based on the problem at hand.