About the role
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