Senior Frontend Engineer, AI Observability & Evals Platform

About Us

At Lang Chain, 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. Lang Chain is a place where your contributions can shape how this technology shows up in the real world.

Today, Lang Chain, Lang Graph, Lang Smith, and Fleet are used by teams shipping real AI products across startups and large enterprises. Millions of developers trust Lang Chain 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, CA, New York, Boston )

We’re looking to bring on an experienced frontend engineer to develop and enhance new features on Lang Smith, our enterprise platform product for LLM application observability, testing, and debugging.

What You Will Do

• 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

What You Will Bring

• Extensive front-end engineering experience with strong proficiency in React, Java

Script and TypeScript:

• 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

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.

Benefits

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