Senior Software Engineer, Agent Platform

Senior Software Engineer - Agent Platform

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, powering 167,000 customers, billions of consumer profiles, and hundreds of billions of customer messages and follow‑on conversion data.

Our next big opportunity is to build state‑of‑the‑art AI and machine learning technologies to power products and develop AI agents that automatically create and execute marketing or customer experiences, strategies, and campaigns for any business.

As a Senior Software Engineer, Agent Platform
, you’ll play a key role in designing and scaling the backend systems that power our AI products and agent solutions. This backend‑heavy role gives you opportunities to influence architecture, async processing, and distributed systems. You’ll collaborate closely with product managers, ML engineers, and data scientists to deliver real‑world impact at scale.

This role is hybrid and based in Boston.

How you'll make a difference:

• Design and build backend systems to scale AI solutions for 167k+ customers.
• Contribute to our agentic architecture to support performant AI agents.
• Build tools to tune LLM‑based features, deploy agents, MCP and RAG in production, and evaluate performance using tools like Arize, OpenAI, Bedrock, Lang Chain, vLLM, and Ray.
• Develop reliable, scalable data pipelines and APIs for AI systems.
• Foster a culture of ownership, experimentation, and customer‑first thinking.

Who You Are:

• 5+ years of experience as a backend software engineer, building scalable, distributed systems.
• Strong experience working in production environments and launching ML/AI projects.
• Hands‑on experience with generative AI and agentic AI applications in production.
• Proficient in Python (or similar).
• Comfortable collaborating with cross‑functional technical partners.
• Curious, proactive, and eager to learn.

Nice to Have:

• Experience with big data tools (e.g., Apache Spark, Ray).
• Familiarity with cloud infrastructure (AWS, Terraform, Kubernetes).
• Knowledge of ML frameworks (Huggingface, PyTorch, Tensor Flow, Keras).

Travel: This role may require up to 10% travel for new hire onboarding, client or partner work, team meetings, and industry events. Travel is coordinated in advance.

Equal Opportunity Statement: Klaviyo is committed to a policy of equal opportunity and non‑discrimination. We do not discriminate on the basis of race, ethnicity, citizenship, national origin, color, religion or religious creed, age, sex (including pregnancy), gender identity, sexual orientation, physical or mental disability, veteran or active military status, marital status, criminal record, genetics, retaliation, sexual harassment or any other characteristic protected by applicable law.