Backend Engineer II, ML-Driven Recommendations

Klaviyo Inc.; Boston, Northern (MA, KY); Hybrid; USD 116,000 - 174,000; Full time

Job summary

Klaviyo is hiring a Software Engineer II - Recommendations in Boston to build scalable machine-learning powered product recommendations. You’ll work on backend services, data pipelines, and a vector database, collaborating with ML engineers and product teams.

You will contribute to productionizing models, maintain observability, and own features end-to-end while advancing AI-driven workflows in a fast-paced, on-site environment.

Qualifications

• 2+ years of professional software engineering experience focusing on backend and distributed systems.
• Proficient in Python and open to other languages.
• Comfortable with cloud-native architectures (AWS preferred) and container orchestration (Kubernetes).
• Experience in data-driven decision making and A/B testing; able to instrument experiments.
• Comfortable designing and querying data models in relational, analytical, and NoSQL stores.
• Familiar with modern DevOps practices (CI/CD, monitoring, alerting).
• Track record of owning features end-to-end from design to rollout and monitoring.
• Excellent technical collaborator and communicator across ML Engineers, Software Engineers, PMs, and other teams.
• Self-starter with interest in AI experimentation and responsible AI workflows.

Responsibilities

• Contribute to architecture and evolution of backend services powering product recommendations across Klaviyo experiences.
• Maintain large-scale data processing pipelines (e.g., Apache Spark) for feature creation and model inputs.
• Collaborate with ML engineers and product stakeholders to productionize recommendation models.
• Contribute to development of vector databases powering search and recommendations.
• Ensure data and service observability with metrics, logging, and dashboards.
• Break down projects into milestones with balance between speed and reliability.
• Lead data-driven decision making and A/B testing to guide iterations.
• Participate in on-call and incident response to improve resilience of the stack.
• Integrate AI into development workflows to accelerate testing and monitoring.
• Share knowledge and mentor junior engineers on large-scale data frameworks.

Skills

Python

Backend systems

Distributed systems

Cloud-native

A/B testing

Data modeling

DevOps / CI-CD

On-call / incident response

Communication

AI experimentation

Tools

Apache Spark

Kubernetes

PostgreSQL

MySQL

Redis

Vector databases

Job description

Klaviyo is hiring a Software Engineer II - Recommendations in Boston to build scalable machine-learning powered product recommendations. You’ll work on backend services, data pipelines, and a vector database, collaborating with ML engineers and product teams.

You will contribute to productionizing models, maintain observability, and own features end-to-end while advancing AI-driven workflows in a fast-paced, on-site environment.