Senior Software Engineer

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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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.

Customer Hub is an entrepreneurial team pioneering one of Klaviyo's boldest bets: reinventing how ecommerce brands personalize the shopper journey. We're bringing personalization on-site, building a unified account experience for shoppers across every touchpoint, and turning that into measurable conversion lift. As a nimble group with a 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.

• A proven track record of building high-quality products and systems, with pride in writing clean, high-quality code.
• 5+ 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 working with React and related 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.
• Experience using AI effectively in software development and delivery, leveraging AI tools to build smarter systems and ways of working from the ground up.

• Skills with Python and Django web framework
• Experience working with Typescript
• Experience developing digital marketing or customer data software solutions.
• Experience building cloud-native solutions, ideally with AWS.

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 experience, education or training, and work location.

In addition to base salary, our total compensation package may include participation in the company’s annual cash bonus plan, variable compensation (OTE) for sales and customer success roles, equity, sign-on payments, and a comprehensive range of health, welfare, and wellbeing benefits based on eligibility.

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