Senior Full Stack Engineer, Observability & Evals Platform; LangSmith

Position: Senior Full Stack Engineer, Observability & Evals Platform (LangSmith)
About Lang Chain

At Lang Chain, our mission is to make intelligent agents ubiquitous. We help developers build mission-critical AI applications across the entire agent development lifecycle. Our open source frameworks — Lang Chain and Lang Graph — see over 70+ million downloads per month. Developers rely on Lang Chain for composable integrations and Lang Graph for controllable agent orchestration. Our commercial agent platform, consisting of Lang Smith and Lang Graph Platform, enables teams to build, test, run, and manage agents at scale across their organization.

Founded in 2023, Lang Chain powers top engineering teams at companies like Replit, Lovable, Clay, Klarna, Linked In, and more.

About the role:

In person 5 days/week in San Francisco

We're looking for a Senior Full Stack Engineer for our commercial product Lang Smith, an observability and evals platform. In this role, you'll have the opportunity to shape the technical direction of our platform while working closely with enterprise customers, developer end-users and internal stakeholders.

• Lead the technical architecture and implementation of key product features for Lang Smith, working across our entire Go, Python, and Typescript stack.

• Collaborate closely with product and design teams to iterate on new features.

• Mentor and guide more junior members of the team. Drive aggressive project timelines while ensuring high engineering standards are being met.

• Lead by example in writing clean, maintainable, and well-tested code

How to be successful in this role

• 7+ years of experience in software engineering working on complex platform products

• Fullstack engineering experience with Go or Python on the backend and React + Typescript on the frontend.

• Strong understanding of database systems, particularly Postgres and Redis

• Experience designing and scaling APIs, preferably in a high-performance, data-intensive application

• A “get stuff done” attitude - comfortable shipping fast and iterating based on user feedback

• Strong communicator with the ability to collaborate closely with various internal stakeholders and engage directly with our top-tier customers

• Strong ownership mindset

• Bonus:

Experience with AI/LLM-powered applications, developer tools, or observability platforms

Compensation & Benefits

• Competitive salary and equity stake for role and stage of company. Commensurate with experience.

• Annual salary range: $165,000-$198,000 USD

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