Senior Software Engineer, Agent Platform

Senior Software Engineer, Agent Platform

At Klaviyo, we value the unique backgrounds, experiences and perspectives each Klaviyos brings to our workplace each and every day. We believe everyone deserves a fair shot at success and appreciate the experiences each person brings beyond the traditional job requirements. If you’re a close but not exact match with the description, we hope you’ll still consider applying. Visit klaviyo.com/careers to see how we empower creators to own their own destiny.

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 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, LangChain, 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, TensorFlow, Keras).

Base Pay Range for US Locations:

$148,000 — $222,000 USD

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

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.