Senior Frontend Engineer, Observability & Evals Platform; LangSmith

Senior Frontend Engineer, Observability & Evals Platform (Lang Smith)

About Lang Chain
At Lang Chain, our mission is to make intelligent agents ubiquitous. We provide the agent engineering platform and open source frameworks developers need to ship reliable agents fast. Our open source frameworks, Lang Chain and Lang Graph, see over 90+ million downloads per month and help developers build agents with speed and granular control. Lang Smith offers observability, evaluation, and deployment for rapid iteration, enabling teams to transform LLM systems into dependable production experiences.

Lang Chain is trusted by millions of developers worldwide and powers AI teams at companies like Replit, Clay, Cloudflare, Harvey, Rippling, Vanta, Workday, and more.

About the role
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 & Type Script
• 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 full‑stack and backend developers and UX/UI designers, to enhance usability

In this role, you’re a good fit if you have:

• 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 full‑stack 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
• An ownership mindset; self‑driven and looking for opportunities to make an impact
• Strong computer science fundamentals, ideally with a degree in computer science or related field

Compensation & Benefits

• Competitive base salary, meaningful equity, health and dental coverage, flexible vacation, 401(k), and life insurance. Actual compensation varies by role, level, and location. For EU/UK team members, we provide locally competitive benefits aligned with regional norms and regulations.
• Annual salary range: $155,000–$195,000 USD

Seniority level

Mid‑Senior level

Employment type

Full‑time

Job function

Engineering and Information Technology

Industries

Technology, Information and Internet