Senior Software Engineer - Flows AI

About the Role

At Klaviyo, we believe the future of software lies not in productivity tools for human users but in software that can run and optimize itself based on outcome or reward metrics. We’ve built the infrastructure and application that serve as the interface between businesses and consumers. We now have over 167,000 customers, billions of consumer profiles, and hundreds of billions of customer messages and follow-on conversion data. We have a big opportunity to build state-of-the-art AI and machine learning technologies at Klaviyo to power our products and develop AI agents that can automatically create and execute marketing or customer experiences, strategies, and campaigns for any business.

Our team is looking for a Sr. Software Engineer to join Flows AI. You’ll help build the backend systems and product experiences behind our AI agent capabilities in Klaviyo’s Flows product. Flows is a core part of Klaviyo that helps marketers automate personalized customer journeys across channels, and our team is focused on making those journeys easier to create, manage, and improve with practical AI. You’ll partner closely with product managers, machine learning engineers, and data scientists to deliver customer impact at scale. This is a full-stack role with opportunities to shape architecture, async processing pipelines, and distributed systems.

How You Will Make a Difference

• Drive the technical design and implementation of customer-facing AI capabilities within Klaviyo Flows.
• Own projects end to end, from working through ambiguity and refining requirements to shipping and operating production features.
• Build reliable, scalable full-stack systems, including backend services, async processing pipelines, and product experiences that help marketers create and improve automated journeys.
• Partner proactively with product, design, and engineering teammates to shape priorities and deliver measurable customer value.
• Raise the bar for engineering quality, operational health, and technical strategy in a fast-moving product area.

Who You Are

• 5-7 years of professional experience in full-stack software engineering.
• Have a track record of building and maintaining high-scale, customer-facing product features.
• Bring experience shipping AI-powered product capabilities or other complex, ambiguous product initiatives in production.
• Experience creating human and automated evals to ensure high AI model quality.
• Hands-on experience with one or more front end technologies (React, TypeScript, Angular, Vue, etc.)
• Experience with Python / Django or similarly typed languages.
• Experience with designing and managing scalable databases.
• Experience with asynchronous processing and distributed task queues (Celery, Kafka, SQS, RabbitMQ, Redis).
• Experience with cloud-native architectures (AWS) and container orchestration (Kubernetes); can manage infrastructure and CI/CD pipelines.
• Hands-on experience with building REST APIs, GraphQL, and other middleware development tools.
• Able to operate with a high degree of autonomy, handle ambiguity, and thrive in a fast-moving, startup-like environment.
• Driven by curiosity. You're someone who learns and stays up to date with this rapidly evolving field.
• Comfortable collaborating directly with product managers and customers to shape solutions.
• Thrive in customer-focused, fast-moving environments and help make the team around you more effective.

Nice to Have

• Experience with workflow builders, automation products, or journey-orchestration style systems