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

The role

You will build backend systems that power the LangSmith observability and evals platform. You will work on core services that allow developer teams to monitor and evaluate AI applications at scale.

What you will do

• Design, develop, and maintain backend services and APIs to support LangSmith 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 through root-cause analysis and 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 new features.

Required qualifications

• 4+ years of professional experience in backend engineering working on highly complex products
• Proficiency in one or more backend languages/frameworks
• 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
• Strong communication skills
• Customer centricity and ownership mentality

Nice to have

• Python and/or Go
• Experience with database systems (Postgres, Redis, Clickhouse)
• Experience with cloud platforms (AWS, GCP, Azure)
• Familiarity with fullstack or frontend engineering
• Performance tuning
• Debugging production issues

Benefits

• Medical coverage
• Dental coverage
• Vision coverage
• Flexible vacation
• 401(k) plan
• Meals on in-office days in the US
• Meaningful equity

About the company

LangChain builds the foundation for agent engineering, offering tools and a platform for building, evaluating, deploying, and operating AI agents at scale.