Front End Engineer (Js, UX/UI)

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, 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 the trust of major industry players including teams at Klarna, Clay, Coinbase, Workday, Lyft, Cloudflare, Harvey, Rippling, Vanta, LinkedIn, Monday.com, Nvidia, and Bridgewater. About The Role This position is based onsite in Boston. We are seeking an experienced frontend engineer to join our team and contribute to the development and enhancement of LangSmith, our enterprise platform for LLM application observability, testing, and debugging. As a key member of the team, you will be responsible for creating innovative, high-quality user interfaces that improve the usability and performance of our platform. Your work will directly impact how our clients monitor, evaluate, and optimize AI systems at scale. You will collaborate closely with full-stack developers, backend engineers, and UX/UI designers to translate design concepts into functional, efficient, and engaging web applications. This role offers a unique opportunity to work at the forefront of AI technology and contribute to shaping the future of AI observability and reliability in production environments. Qualifications Extensive experience in front-end development with a strong proficiency in React, JavaScript, and TypeScriptHands-on experience with front-end development tools such as Babel, Vite, Webpack, NPM, and YarnFamiliarity with REST APIs and experience working collaboratively with backend and full-stack engineersKnowledge of modern authorization mechanisms, including JWTsStrong understanding of user experience principles, with a passion for building clean, intuitive, and engaging interfacesExcellent written and verbal communication skills, capable of explaining technical concepts clearly to diverse audiencesAbility to thrive in a fast-paced, start-up environment and adapt to unstructured scenariosSelf-driven with a strong ownership mindset and a desire to make impactful contributionsDegree in Computer Science or a related field, with strong fundamental knowledge in computer science principles Responsibilities Develop new user-facing features using React and TypeScript to enhance platform capabilitiesBuild and maintain reusable components and front-end libraries for scalable developmentTranslate wireframes and design prototypes into high-quality, performant codeOptimize web components for maximum speed and responsiveness across various devices and browsersCollaborate with cross-functional teams including backend developers and UX/UI designers to improve usability and functionalityParticipate in code reviews, testing, and debugging to ensure high standards of quality and reliabilityContribute to the continuous improvement of development processes and best practicesStay updated with the latest trends and technologies in front-end development to bring innovative ideas to the team Benefits Competitive annual salary ranging from $175,000 to $240,000 USDComprehensive medical, dental, and vision coverageFlexible vacation policy to support work-life balance401(k) retirement plan with company matchingMeals provided on in-office days in the USEquity options to share in the company's growth and successOpportunities for professional development and career advancementCollaborative and innovative work environment Equal Opportunity LangChain is committed to creating a diverse and inclusive workplace. We are an equal opportunity employer and do not discriminate based on race, color, religion, gender, gender identity or expression, sexual orientation, national origin, age, disability, or any other protected status under applicable law. We believe that a diverse team fosters innovation and drives our mission forward, and we welcome applicants from all backgrounds to apply.