Software Engineer II - Flows Experience

Klaviyo • Boston, MA

2d • Onsite

About The Position

Klaviyo’s Flows Experience team builds the tools marketers use to create and manage automated marketing journeys, including the canvas, triggers, filters, actions, analytics, and APIs for developers and AI tools. The team’s mission is to make sophisticated marketing automation easy to use and trustworthy, catch mistakes before they affect revenue, and support growing accounts.

This full-stack role owns features end to end, from the React canvas to the Python services and APIs. The engineer works with the Flows Platform team, product, and design to deliver customer-facing improvements, evolve APIs, improve performance and reliability, and help the product scale. The role also contributes technical leadership through design reviews, mentorship, operational excellence, and AI-assisted development practices. The position is onsite in Boston, Massachusetts, five days a week.

Requirements

• Experience building and shipping products that customers rely on, with care for both user experience and code quality.
• Strong full-stack skills, with deep expertise in at least one area such as complex front-end applications, API design, or backend performance, and comfort working in other areas.
• Ability or interest in solving problems at the intersection of user experience and systems, such as canvas performance, workflow usability, slow queries, or queue processing.
• Ability to work effectively on a small, autonomous team, own outcomes, and collaborate broadly.
• Curiosity about how AI changes both product development, including agents that build flows, and engineering practices.

Responsibilities

• Own major parts of the Flows product—including the builder, analytics, version history, and management surfaces—from design through launch and operation.
• Design and evolve public and internal Flows APIs used by customers, partners, and AI agents.
• Improve performance and reliability for large flows and accounts, including canvas rendering, analytics queries, and APIs under heavy load.
• Build guardrails such as validation, safe defaults, clear feedback, and recovery options to prevent costly mistakes.
• Partner with Flows Platform on the contract between the product and the flow engine so new capabilities can scale.
• Contribute technical leadership through design reviews, mentorship, operational excellence, and modern AI-assisted development practices.
• Ship iteratively, using data and customer feedback to improve products in collaboration with product and design.

What This Job Offers

• Job Type: Full-time
• Career Level: Mid Level
• Education Level: No Education Listed