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

About the role

In person 5 days/week in San Francisco, Boston, MA, New York. We are looking for a Senior Backend Engineer to join us.

What You'll Do

• 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.
• Create and maintain technical documentation, including system design and API references.
• Work closely with full-stack engineers, product managers, and product designers on rolling out new features.

Requirements

5+ years of professional experience in backend engineering working on highly complex products

Proficiency in one or more backend languages/frameworks, ideally Python or Go

Strong understanding of API design and building reliable data services

Experience with high-throughput or mission-critical systems

Demonstrated ability to optimize backend services for performance and reliability

Experience with database systems (Postgres, Redis, Clickhouse), and cloud platforms (AWS, GCP, Azure)

Strong communication skills, with the ability to collaborate cross-functionally

Customer centricity and ownership mentality