Senior Frontend Engineer, Observability & Evals Platform; LangSmith

About Lang Chain

At Lang Chain, our mission is to make intelligent agents ubiquitous. We help developers build mission-critical AI applications across the entire agent development lifecycle. Our open source frameworks — Lang Chain and Lang Graph — see over 70+ million downloads per month. Developers rely on Lang Chain for composable integrations and Lang Graph for controllable agent orchestration. Our commercial agent platform, consisting of Lang Smith and Lang Graph Platform, enables teams to build, test, run, and manage agents at scale across their organization.

Founded in 2023, Lang Chain powers top engineering teams at companies like Replit, Lovable, Clay, Klarna, Linked In, and more.

In person 5 days/week in San Francisco, CA, New York, Boston, London, or Amsterdam

We’re looking to add a frontend engineer to develop and enhance new features on Lang Smith, working on our enterprise platform product for LLM application observability, testing, and debugging. You will:

• Develop new user-facing features using React & Typescript
• Build reusable components and front-end libraries for future use
• Translate designs and wireframes into high-quality code
• Optimize components for maximum performance across a vast array of web-capable devices and browsers
• Collaborate with fullstack and backend developers and UX/UI designers, to enhance usability

• Front-end engineering experience with strong proficiency in React, JavaScript and Type
• Script
• Hands-on experience with front-end development tools like Babel, Vite, Webpack, NPM, and Yarn
• Familiarity with REST APIs and experience working closely with fullstack and backend engineers
• Knowledge of modern authorization mechanisms, such as JWTs
• A passion for user experience, design and building clean, engaging, and intuitive interfaces
• Strong written and oral communication skills, with the ability to explain technical concepts clearly and concisely to both technical and non-technical stakeholders
• The DNA to thrive in a start-up, fast-paced environment. Views unstructured environments as an opportunity to figure out the most impactful work and help define the future success of the company
• An ownership mind-set. You are self-driven and look for opportunities to make an impact.
• Strong computer science fundamentals, ideally with a degree in computer science or related field

• Competitive salary and equity stake for role and stage of company. Commensurate with experience.
• Annual salary range: $155,000-$195,000 USD