Software Engineer II - Flows Experience

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

Software Engineer II - Flows

Onsite in Boston, MA 5 days a week

Flows is how tens of thousands of brands automate their marketing on Klaviyo, from welcome series and abandoned-cart reminders to complex multi-channel journeys that reach 100M+ consumers. The Flows Experience team builds everything a marketer touches in a flow: the canvas, triggers, filters and actions they configure, the analytics they use to decide what to do next, and the APIs that developers and AI tools use to build flows for them. Our mission: Flows should be the easiest, most trusted place to run sophisticated marketing automation. Complex journeys should feel simple, mistakes should get caught before they cost revenue, and the product should keep up as an account grows.

We want a Full Stack Engineer who likes owning features end to end, from the React canvas down to the Python services and APIs underneath. You’ll work closely with Flows Platform, the team that runs the engine behind every flow, and with product and design, to ship work customers notice right away. Recently the team made large flows open up to 70% faster, launched an API (also in the Klaviyo MCP) that lets developers and AI agents safely edit live flows, and raised webhook throughput 20x.

How you’ll make a difference

• Own major parts of the Flows product (the builder, analytics, version history, management surfaces) from design through launch and operation
• Design and evolve the public and internal Flows APIs that define how a flow can change. Customers, partners and AI agents all build on them.
• Make the product fast and reliable for very large flows and very large accounts, whether that means canvas render performance, a slow analytics query or an API under heavy load
• Build guardrails that catch mistakes before they cost a brand revenue: validation, safe defaults, clear feedback and easy recovery
• Partner with Flows Platform on the contract between the product and the engine, so new capabilities scale from day one
• Raise the bar for your team as a technical leader through design reviews, mentorship, operational excellence and modern, AI-assisted ways of building

Who you are

• You’ve built and shipped products that customers rely on, and you care about the user experience as much as the code
• You’re strong across the stack. You know at least one area deeply (complex front-end apps, API design, or backend performance) and are comfortable working in the others.
• You enjoy hard problems at the line between UX and systems: a canvas that lags with 200 nodes, a workflow with too many clicks, a query that times out, a queue that won’t drain
• You ship early and often, use data and customer feedback to iterate, and work closely with product and design
• You thrive on a small, autonomous team where you own outcomes and collaborate widely to get them right
• You’re curious about how AI changes both what we build (agents that build flows) and how we build it

Technologies we use (not exhaustive)

• React, TypeScript, JavaScript
• Python, Django, Celery
• MySQL, Redis, RabbitMQ, Kafka
• AWS, Terraform, and modern observability and CI/CD tooling

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:

$116,000 - $174,000 USD

This role may require up to 10% travel for purposes such as new hire onboarding, client or partner work if applicable, team meetings, and industry events. Travel is coordinated in advance.

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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