Senior Backend Software Engineer, AI Observability & Evals Platform (LangSmith)

Job summary

Responsibilities

We are looking for a Senior Backend Engineer to join our growing engineering team in Boston. In this role you will be building the backend systems that power LangSmith, LangChain’s observability and evals platform.

• Design, develop, and maintain backend services and APIs to support LangSmith’s tracing, monitoring, and evaluation workflows.
• Collaborate on architectural decisions to ensure systems are performant and maintainable.
• Optimize storage and query performance for high-volume observability and evaluation data.
• Ensure system reliability through strong testing, monitoring, and alerting practices.
• Troubleshoot and resolve production issues, performing root-cause analysis and implementing long-term fixes.

What they're looking for

• 4+ years of professional experience in backend engineering working on highly complex products
• Proficiency in one or more backend languages/frameworks, ideally Python and/or Go
• Strong understanding of API design and building reliable data services.
• Experience with high-throughput, mission-critical systems.
• Demonstrated ability to optimize backend services for performance and reliability.

Tech stack

• LangGraph
• Python
• PostgreSQL
• AWS
• GCP
• Azure