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.
Klaviyo is looking for a Senior Software Engineer to join the Flows Platform team. In this role, you will help build and operate the core engine that powers all automated lifecycle programs at Klaviyo. You’ll play a critical part in delivering robust, high-scale backend solutions that process billions of events, send millions of messages, and ensure our customers’ automations run reliably and without delay.
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 Platform team, we focus on the core of Klaviyo’s automation engine, ensuring that hundreds of millions of actions per day are processed accurately and efficiently to power user workflows. Our work revolves around the core backend systems that determine who receives a message and when, handling complex logic for triggering, filtering, and scheduling at massive scale. We also manage the data stores and infrastructure that support these operations, ensuring reliability while we actively re-architect our stack to support the next generation of event-driven features.
We are responsible for:
- Core Execution Engine: The logic for flow triggering, evaluation (filtering/branching), and action execution. We ensure that every event is processed accurately and efficiently.
- Scheduling & Orchestration: Managing time-based logic, delays, and the dispatching of millions of scheduled actions per day.
- High-Scale Infrastructure: Owning the execution data stores and pipelines that must run reliably at huge scale.
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.
What We’re Looking For
- 6+ years of experience in a software engineering role with a focus on backend systems and high-volume data processing.
- Deep experience building robust services and APIs using Python and Django (or similar frameworks).
- Demonstrated experience designing large-scale systems, managing technical debt, and making high-level architectural decisions.
- Distributed systems knowledge and deep experience working with asynchronous task queues (e.g. Celery, RabbitMQ, Pulsar) and understanding the challenges of eventual consistency and distributed state.
- Expertise in relational databases (MySQL/Aurora) and high-scale NoSQL stores (Redis or DynamoDB).
- A focus on writing clean, maintainable code, participating in code reviews, and leading robust testing practices (unit, integration, and load testing).
- A passion for coaching junior engineers, conducting code reviews, and fostering a collaborative and high-performing engineering culture.
- Experience working in fast-paced environments and collaborating with other engineering teams to solve cross-functional problems.
- Experience with Infrastructure as Code (Terraform) and container orchestration (Kubernetes).
- Experience building cloud-native solutions, ideally on AWS.
- Experience using AI coding tools like Claude Code or Cursor to accelerate development.
- Experience with Event-Driven Architecture and streaming technologies like Pulsar or Kafka.
- Background in building platforms that support other engineering teams.
- Background in digital marketing, customer data software, or building analytics products.
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.
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.
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What We Do
Klaviyo (NYSE: KVYO) is the B2C CRM. Powered by its built-in data platform and AI, Klaviyo combines marketing automation, analytics, and customer service into one unified solution, making it easy for businesses to know their customers and grow faster. Klaviyo (CLAY-vee-oh) helps over 183,000 brands like Mattel, Glossier, Daily Harvest, and Liquid Death deliver 1:1 experiences at scale, improve efficiency, and drive revenue.
Why Work With Us
We refer to our employees as ‘Klaviyos’, and we make up a diverse community united around shared values: We’re curious, collaborative, driven, innovative, fun, and fully ourselves at work. No matter which team you join, your work won’t just impact Klaviyo. It’ll help empower our customers and enable creators across the globe to own their destinies.
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