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. Want to learn more about life at Klaviyo? Visit to see how we empower creators to own their own destiny.

About the Role

Klaviyo is looking for a Senior 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 Senior Software Engineer, 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.

On the Flows Insight & Management team, we focus on crafting an exceptional user experience for the Flows product area which empowers users to to build, manage, and analyze automated workflows seamlessly. Our work revolves around an intuitive visual editor that lets users create and modify flows with ease, as well as the rich insights and analytics that help them understand how their flows are performing. We also manage APIs that integrate with other services, creating a powerful ecosystem for users to drive automation in new and exciting ways.

Collaboration is key to what we do. We actively partner with engineering teams across the organization, giving us exposure to diverse parts of the product and opportunities to impact various projects. This keeps us engaged with a variety of challenges and solutions, as we're always learning and evolving.

Looking to the future, our team is focused on expanding the capabilities of Flows. We'll be enhancing our flow editor and ecosystem to make it even easier to build and expand on flows. We're also building smarter recommendations and actionable insights to help users optimize their flows. With our continued evolution, we envision Flows not just as a tool, but as a platform that empowers teams to do more, build more, and connect seamlessly.

How You Will Make a Difference:

• Drive critical platform improvement projects that enhance performance and scalability
• Optimize real-time pipelines for accurate usage tracking at scale (e.g., campaign volumes)
• Deliver billing transparency improvements—both platform and customer-facing—through incremental value, fast learning, and unlocks that drive clarity, trust, and reduced friction
• Focused on unlocking impact by using the right tools for the job, leaning into AI, and always looking for opportunities to make a meaningful difference
  Own and evolve key components of an event-driven architecture powering high-reliability systems

Who You Are:

• Experienced engineer with deep expertise in Python and Django—or a fast, adaptable learner who thrives in any stack with the right tools.
• A proven track record of building high-quality products and systems, with a focus on writing clean, maintainable code
• 5+ 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
• Skilled in working with cloud technologies, particularly AWS
• Experienced in event-driven architecture using tools like Kafka, SQS, or PubSub
• Track record of building and maintaining reliable, large-scale production systems
• Skilled at mentoring teammates and fostering growth across the engineering org
• Comfortable making fast, high-impact decisions and communicating clearly with both the team and stakeholders in dynamic environments

Technologies We Use:

• Languages & Frameworks: Python, Django, React, TypeScript
• Infrastructure: AWS (S3, Athena), Redis, MySQL

We use Covey as part of our hiring and / or promotional process. For jobs or candidates in NYC, certain features may qualify it as an AEDT. As part of the evaluation process we provide Covey with job requirements and candidate submitted applications. We began using Covey Scout for Inbound on April 3, 2025.

Please see the independent bias audit report covering our use of Covey here

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 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. 

Your recruiter can provide more details about the specific salary/OTE range for your preferred location during the hiring process.

Base Pay Range For US Locations: $152,000—$228,000 USD

Get to Know Klaviyo

We're Klaviyo (pronounced clay-vee-oh). We empower creators to own their destiny by making first-party data accessible and actionable like never before. We see limitless potential for the technology we're developing to nurture personalized experiences in ecommerce and beyond. To reach our goals, we need our own crew of remarkable creators—ambitious and collaborative teammates who stay focused on our north star: delighting our customers. If you're ready to do the best work of your career, where you'll be welcomed as your whole self from day one and supported with generous benefits, we hope you'll join us.

AI fluency at Klaviyo includes responsible use of AI (including privacy, security, bias awareness, and human-in-the-loop). We provide accommodations as needed. 

By participating in Klaviyo's interview process, you acknowledge that you have read, understood, and will adhere to our Guidelines for using AI in the Klaviyo interview Process. For more information about how we process your personal data, see our Job Applicant Privacy Notice.

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.

IMPORTANT NOTICE: Our company takes the security and privacy of job applicants very seriously. We will never ask for payment, bank details, or personal financial information as part of the application process. All our legitimate job postings can be found on our official career site. Please be cautious of job offers that come from non-company email addresses ), instant messaging platforms, or unsolicited calls.
 
By clicking "Submit Application" you consent to Klaviyo processing your Personal Data in accordance with our Job Applicant Privacy Notice.  If you do not wish for Klaviyo to process your Personal Data, please do not submit an application.  You can find our Job Applicant Privacy Notice here and here (FR).

---