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.

As a Sr. AI Engineer at Klaviyo, you’ll play a key role in designing and building scalable backend systems and user experiences that power our AI products and AI agent solutions. You’ll partner closely with product managers, machine learning engineers, and data scientists, to drive real-world impact at scale. This is a backend-heavy role with opportunities to influence architecture, async processing pipelines, distributed systems, and more.

How You Will Make a Difference

• Design and build backend systems that support scaling our AI solutions for 167K+ customers.

• Develop robust, reliable and scalable data collection and processing pipelines for machine learning models to train and consume.

• Develop robust, reliable and scalable services to serve AI models in production environments.

• Contribute to evolving our agentic architecture — making our AI agents more self-sufficient and performant.

• Contribute to a culture of ownership, experimentation, and customer-centric product thinking.

Who You Are

• 5–7 years of professional experience in software engineering, with a strong focus on backend systems and distributed architectures.

• Have hands-on experience building and deploying generative AI and agentic AI applications into production, with expertise in prompt engineering, few-shot learning, fine tuning and evaluation.

• Experienced backend engineer with a strong track record of building scalable, distributed systems, especially in the service of AI agent capabilities.

• Proficient in Python and modern backend frameworks (FastAPI, Django preferred).

• Experience creating human and automated evals to ensure high AI model quality.

• Proficient in big data tools such as Apache Spark and Hadoop.

• Deep experience with asynchronous processing and distributed task queues (Celery, Kafka, SQS, RabbitMQ, Redis).

• Strong understanding of database technologies and ORMs (SQLAlchemy, Alembic).

• Comfortable with cloud-native architectures (AWS) and container orchestration (Kubernetes); can manage infrastructure and CI/CD pipelines.

• Skilled at designing and building robust APIs.

• 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.

Nice to Have

• Trained ML models in the past and deployed them in production systems to generate impact to businesses.

• Experience in reinforcement learning.

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