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, our platform includes LangSmith (Observability, Evaluation, Deployment, Fleet, and Sandboxes), our open source frameworks (LangChain, LangGraph, and Deep Agents), and the newly launched LangSmith Engine for autonomous agent improvement. We have 100M+ monthly open source downloads, 6,000+ active LangSmith customers, and 5 of the Fortune 10 use LangSmith in production (+ 35% of the Fortune 500 overall), including teams at Klarna, Clay, Coinbase, Workday, Lyft, Cloudflare, Harvey, Rippling, Vanta, LinkedIn, Monday.com, Nvidia, and Bridgewater.
About The TeamThe LangSmith team owns and builds LangChain's core platform for observability, evaluation, and production reliability of AI systems. From tracing and annotation to run rules, evaluations, and beyond, this team owns LangSmith end-to-end. If you want to define what great AI observability looks like at production scale, this is where that work gets done.
About the roleThis role is onsite 5 days/week in Boston, MA
We're looking for a Senior Fullstack Engineer to work on LangSmith. In this role, you'll have the opportunity to shape the technical direction of our platform while working closely with our enterprise customers, developer end-users, and cross functional 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.
Help drive aggressive project timelines while ensuring high engineering standards are being met.
Lead by example in writing clean, maintainable, and well-tested code.
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-$240,000 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.
BenefitsBenefits include medical, dental, and vision coverage, flexible vacation, a 401(k) plan, meals on in-office days in the US and more.
Skills Required
- 5+ years of software engineering experience working on complex platform products
- Fullstack engineering 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
- Ability to ship quickly and iterate based on user feedback
- Strong communication and collaboration skills, including direct engagement with customers
- Strong ownership mindset
- Experience with AI/LLM-powered applications, developer tools, or observability platforms
What We Do
LangChain is the platform for building reliable agents. Our products power top engineering teams — from fast-growing startups like Lovable, Mercor, and Clay to global brands including AT&T, Home Depot, and Klarna. LangGraph is a low-level orchestration framework for building controllable agents and long-running workflows. It’s used in production by teams at Replit, Uber, LinkedIn, GitLab, and more. LangSmith offers unified evaluation and monitoring to help developers debug, evaluate, and improve their agents at scale. LangChain provides hundreds of integrations and composable components, making it easy to connect with the latest models, tools, and databases — with minimal engineering overhead. Together, these tools help teams build, deploy, and manage enterprise-grade agents, faster.
