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

About Us:

At LangChain, our mission is to make intelligent agents ubiquitous. We build the foundation for agent engineering in the real world, helping developers move from prototypes to production-ready AI agents that teams can rely on. We began as widely adopted open-source tools and have grown to also offer a platform for building, evaluating, deploying, and operating agents at scale.

Today, LangChain, LangGraph, LangSmith, and Agent Builder are used by teams shipping real AI products across startups and large enterprises. Millions of developers trust LangChain to power AI teams at companies like Replit, Clay, Coinbase, Workday, Lyft, Cloudflare, Harvey, Rippling, Vanta, and 35% of the Fortune 500.

With $125M raised at Series B from IVP, Sequoia, Benchmark, CapitalG, and Sapphire Ventures, we’re at a stage where we’re continuing to develop new products, growth is accelerating, and all team members have meaningful impact on what we build and how we work together. LangChain is a place where your contributions can shape how this technology shows up in the real world.

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. In this role you will be building the backend systems that power LangChain’s observability and evals platform. You will work on the core services that allow developers to monitor and evaluate their AI applications at scale. While the focus is on backend feature development, familiarity with fullstack or frontend engineering, performance tuning, and debugging production issues would be extremely valuable.

What You Will 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.

What You Will Bring:

• 5+ years of professional experience in backend engineering

• 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

Compensation & Benefits:

• We offer competitive compensation that includes base salary, meaningful equity, and benefits such as health and dental coverage, flexible vacation, a 401(k) plan, and life insurance. Actual compensation will vary based on role, level, and location. For team members in the EU and UK, we provide locally competitive benefits aligned with regional norms and regulations.

• Annual salary range: $175,000- $225,000