Software Engineer II – Messaging Infrastructure

About the role

Klaviyo is looking for a Software Engineer II to join its Messaging Infrastructure team. You will help build and maintain the core platform that delivers billions of messages across email, SMS, push, and other channels, ensuring high scalability and reliability.

Key responsibilities

• Design, develop, and own features and services used by hundreds of thousands of customers daily.
• Build and optimize a highly‑scalable, highly‑available campaign pipeline processing hundreds of millions of messages.
• Collaborate with cross‑functional teams on design decisions, implementation, and engineering best practices.
• Introduce and evaluate new technologies to evolve the platform.
• Improve experimentation, development processes, and mentor fellow engineers.
• Participate in technical interviews and act as a subject‑matter expert.

Required profile

• 4+ years of experience in software engineering.
• Experience architecting, building, and delivering at least one complex system.
• Strong understanding of large‑scale system architecture, trade‑offs, and design patterns.
• Passion for diagnosing performance and scalability issues and delivering breakthrough solutions.

Required skills