Backend Engineer, ML-Powered Recommendations

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

Job summary

Klaviyo Boston is seeking a Software Engineer II for the Recommendations Platform Team, onsite 5 days a week. You will help build and scale backend services powering product recommendations across Klaviyo’s experiences, leveraging large-scale data pipelines and modern ML workflows.

You will collaborate with ML engineers and product stakeholders to productionize models, design feature interfaces, and deploy batch and real-time inference systems, while ensuring reliability and rapid

Qualifications

• 2+ years of professional software engineering experience with backend and distributed systems at scale.
• Proficient in Python and open to other languages.
• Cloud-native architectures (AWS preferred) and container orchestration (Kubernetes).
• Experience in data-driven decision making and A/B testing.
• Comfortable designing and querying data models in relational, analytical, and NoSQL datastores.

Responsibilities

• Architect and evolve backend services powering product recommendations.
• Maintain large-scale data pipelines transforming events into features for models.
• Collaborate with ML engineers to productionize models and define interfaces.
• Develop the vector database powering recommendations and semantic search.
• Ensure observability with metrics, logging, and dashboards; drive reliability and uptime.
• Break down projects into milestones with clear timelines and measurable outcomes.
• Lead data-driven decision making and AB testing; interpret results to guide iterations.
• Participate in on-call incident response to improve resilience.

Skills

Python

Backend

Distributed systems

AWS

Kubernetes

Spark

A/B testing

Data modeling

Tools

PostgreSQL

Redis

Vector DB

Job description

Klaviyo Boston is seeking a Software Engineer II for the Recommendations Platform Team, onsite 5 days a week. You will help build and scale backend services powering product recommendations across Klaviyo’s experiences, leveraging large-scale data pipelines and modern ML workflows.

You will collaborate with ML engineers and product stakeholders to productionize models, design feature interfaces, and deploy batch and real-time inference systems, while ensuring reliability and rapid