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Salary: USD 180,000 - 240,000 / annual
LangChain is seeking a Senior Fullstack Software Engineer to shape the technical direction of LangSmith, our observability and evaluation platform for AI agents. You'll work across our Go, Python, and TypeScript stack, leading the technical architecture and implementation of key product features while collaborating closely with product, design, and enterprise customers.
In this role, you will lead the technical architecture and implementation of key product features for LangSmith, working across the entire Go, Python, and TypeScript stack. You'll collaborate closely with product and design teams to iterate on new features, mentor and guide junior team members, and drive aggressive project timelines while maintaining high engineering standards. You'll lead by example in writing clean, maintainable, and well-tested code.
LangChain is a developer platform and framework for building LLM applications and agents. Founded in 2023, the company has raised $125M at Series B from top-tier investors including IVP, Sequoia, Benchmark, CapitalG, and Sapphire Ventures. The platform includes LangSmith (observability, evaluation, deployment, fleet, and sandboxes), open-source frameworks (LangChain, LangGraph, and Deep Agents), and the newly launched LangSmith Engine for autonomous agent improvement. The company serves 100M+ monthly open-source downloads, 6,000+ active LangSmith customers, and 5 of the Fortune 10 use LangSmith in production, with 35% of the Fortune 500 overall using the platform.
REQUIREMENTS:
- 5+ 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 PostgreSQL and Redis
- Experience designing and scaling APIs, preferably in high-performance, data-intensive applications
- "Get stuff done" attitude—comfortable shipping fast and iterating based on user feedback
- Strong communicator with ability to collaborate closely with internal stakeholders and engage directly with top-tier customers
- Strong ownership mindset
- Bonus: Experience with AI/LLM-powered applications, developer tools, or observability platforms
About LangChain
AI / Data / Infrastructure — developer platform and framework for building LLM applications and agents.
