Senior Fullstack Engineer, AI Observability & Evals Platform

LangChain; New York (NY); On-site; USD 175,000 - 225,000; Full time

Benefits offered by this job

Medical, dental, and vision coverage

Flexible vacation

401(k) plan

Meals on in-office days

Job summary

LangChain, based in New York, is hiring a Senior Fullstack Engineer for LangSmith, their observability platform. The role demands strong skills in Go and Python, with experience in developing platform products. Responsibilities include leading technical architecture and mentoring junior team members. The position offers a competitive salary range of $175,000 to $225,000 USD along with comprehensive benefits including medical coverage and a 401(k) plan.

Qualifications

• 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 Postgres and Redis.

Responsibilities

• Lead the technical architecture and implementation of key product features for LangSmith.
• Collaborate closely with product and design teams to iterate on new features.
• Mentor and guide more junior members of the team.

Skills

Software Engineering

Fullstack Development

Go

Python

React

Typescript

Postgres

Redis

API Design

Team Collaboration

Job description

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.

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.

Today, LangChain, LangGraph, LangSmith, and Fleet 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.

About The Role

In person 5 days/week in San Francisco.

We're looking for a Senior Fullstack Engineer for our commercial product LangSmith, 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.

What You Will Do

• Lead the technical architecture and implementation of key product features for LangSmith, 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.

What You Bring

• 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 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

• Annual salary range: $175,000‑$225,000 USD

Compensation Philosophy

We offer competitive compensation that includes base salary, variable compensation for relevant roles, meaningful equity, benefits, and perks. Actual compensation and offerings will vary based on role, level, and location. Team members in the EU, UK, and APAC receive locally competitive benefits aligned with regional norms and regulations.

Benefits

Benefits include medical, dental, and vision coverage, flexible vacation, a 401(k) plan, meals on in‑office days in the US and more.