Senior Software Engineer - Product

Position: Senior Software Engineer - New Product
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.

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About the Role

Our team is looking for a Senior Full Stack Engineer to lead key initiatives that will enhance our product offerings and support our company’s growth. In this role, you'll play a crucial part in shaping outcomes by developing innovative end-to-end solutions using both front‑end and back‑end technologies. You’ll optimize existing products and create new solutions that redefine what’s possible for our customers.

As a Senior Engineer, you’ll tackle complex challenges, develop multiple solutions, and evaluate business and technical trade‑offs to determine the best path forward. You’ll also act as a leader and mentor, and drive key technology decisions. Additionally, you’ll be responsible for deploying well‑designed, thoroughly tested solutions that ensure reliability and performance.

The New Products team drives Klaviyo’s most ambitious innovations—creating and scaling the company’s boldest new bets. As a nimble group with a flat structure and fast‑moving culture, we prioritize simplicity, speed, and impact. Every team member is expected to take radical ownership—rolling up their sleeves, collaborating across disciplines, and pushing beyond traditional role boundaries to make things happen. Success in this role means delivering exceptional work that sets the standard for velocity and results company‑wide, while helping shape Klaviyo’s future through experimentation, creativity, and executional excellence.

What We’re Looking For

• A proven track record of building high‑quality products and systems, with pride in writing clean, high‑quality code.

• 7+ years of experience in a software engineering role.

• Strong experience developing end‑to‑end software solutions or extensive experience with both front‑end and back‑end technologies.

• Experience leading projects and being accountable for their outcomes.

• Experience mentoring team members or driving initiatives that help the team learn new skills.

• Experience conducting code reviews and running a robust testing cycle.

• Experience working in agile, fast‑paced environments.

• 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.

• Transform workflows by putting AI at the center, building smarter systems and ways of working from the ground up.

Nice to Have

• Skills with Python and related technologies

• Skills with React and related technologies

• Experience developing digital marketing or customer data software solutions.

• Experience with machine learning.

• Experience building cloud‑native solutions, ideally with AWS.

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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…