Senior Software Engineer - Billing Usage Platform

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 careers.klaviyo.com to see how we empower creators to own their own destiny.

Why You Should Join the Billing Usage Platform Team:

The Billing Usage Platform team sits at the core of our billing and usage infrastructure powering the systems that ensure customers are billed transparently and accurately based on product usage. From tracking millions of real-time events to ensuring billing clarity for both enterprise and self-service customers, our work enables seamless and scalable experiences that support business growth.

As a Senior Software Engineer, you’ll play a key role in advancing this platform enhancing reliability, scalability, and performance. You’ll work alongside a collaborative, high-performing team tackling infrastructure and architecture challenges that span real-time pipelines, reporting, and integrations with key customer and product data. If you're excited about solving complex platform problems with tangible customer impact, this team is for you.

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 backend engineer with deep expertise in Python and Django—or a fast, adaptable learner who thrives in any stack with the right tools.
• Familiar with frontend development using React and TypeScript (a plus, not required)
• 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
• Comfortable contributing to platform-level development with customer-facing impact
• 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
• Architecture & Messaging: Kafka, SQS, REST/HTTP, gRPC

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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. Please visit Klaviyo Rewards