Senior Fullstack Engineer (Go/Python/React)

Location: San Francisco, CA, United States; on-site

Annual base salary: $180,000–$240,000 USD, plus variable compensation, equity, benefits, and perks.

Company

LangChain builds open-source frameworks and commercial infrastructure for developing, evaluating, deploying, and operating AI agents at scale.

What you will do

• Lead the technical architecture and implementation of key LangSmith product features across the Go, Python, and TypeScript stack.
• Build and scale an observability and evaluation platform for AI-powered applications.
• Collaborate with product and design to iterate on new features.
• Work directly with enterprise customers, developer end-users, and internal stakeholders.
• Mentor junior engineers and drive projects while maintaining high engineering standards.
• Write clean, maintainable, and well-tested code.

Requirements

• 5+ years of software engineering experience working on complex platform products.
• Fullstack experience with Go or Python on the backend and React with 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.
• Strong communication, ownership, and collaboration skills, including direct engagement with customers.
• Ability to work on-site in San Francisco, CA.

Nice to have

• Experience with AI or LLM-powered applications.
• Experience with developer tools or observability platforms.

Culture & Benefits

• Meaningful opportunity to shape the technical direction of LangSmith and influence product development.
• Medical, dental, and vision coverage.
• Flexible vacation.
• 401(k) plan and meals on US in-office days.
• Competitive benefits aligned with regional norms and regulations for team members in the EU, UK, and APAC.