# Senior Fullstack Engineer, AI Observability & Evals Platform

**Company:** [LangChain](https://hotfix.jobs/companies/langchain)
**Location:** Boston, MA, New York, NY
**Role:** Fullstack Engineering
**Salary:** $175k – $240k/yr
**Experience:** 5+ years
**Skills:** Go, Python, TypeScript, React, Postgres, Redis, API Design, Api Scaling, Ai Applications, Llm Applications, Developer Tools, Observability Platforms
**Posted:** 2026-09-12

> Senior full-stack engineer leading architecture and implementation for LangSmith’s AI observability and evaluation platform. Requires 5+ years of software engineering experience, backend expertise in Go or Python, frontend expertise in React and TypeScript, and experience with databases and scalable APIs.

## Job Description

## Responsibilities
- Lead the technical architecture and implementation of key LangSmith product features across the Go, Python, and TypeScript stack.
- Collaborate with product and design teams to iterate on new features.
- Drive aggressive project timelines while maintaining high engineering standards.
- Write clean, maintainable, and well-tested code.
- Work closely with enterprise customers, developer end-users, and internal stakeholders.

## Requirements
- 5+ years of software engineering experience working on complex platform products.
- Full-stack engineering experience with Go or Python on the backend and React and TypeScript on the frontend.
- Strong understanding of database systems, particularly PostgreSQL and Redis.
- Experience designing and scaling APIs, preferably for high-performance, data-intensive applications.
- Strong communication, collaboration, and ownership skills.
- Ability to ship quickly and iterate based on user feedback.

## Nice to Have
- Experience with AI/LLM-powered applications, developer tools, or observability platforms.

## Compensation and Benefits
- Annual salary range: $175,000-$240,000 USD.
- Variable compensation for relevant roles, meaningful equity, benefits, and perks.
- Medical, dental, and vision coverage.
- Flexible vacation.
- 401(k) plan.
- Meals on in-office days in the United States.

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