Senior Frontend Platform Engineer, Design Systems

About LangChain

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. Today, our platform includes LangSmith, our open source frameworks (LangChain, LangGraph, and Deep Agents), and the newly launched LangSmith Engine.

About the Role

As our product surface area grows, so does the need for a cohesive, scalable, and high-quality UI foundation. We’re looking for a Design Systems Engineer to help build, own, and evolve LangChain’s component library—the foundation that our frontend teams rely on to ship fast without sacrificing quality, accessibility, or consistency.

This role sits at the intersection of Design and Engineering, working closely with designers, product engineers, and platform teams to turn design intent into robust, reusable components and tooling that scale across the product.

What You'll Do

• Build out LangChain’s component library: Design and implement reusable, composable React components that are flexible, accessible, and production-ready.
• Partner closely with designers to translate design systems, tokens, and interaction patterns into code.
• Build reliable UI quality systems: Develop design system tooling and improve workflows around theming, tokens, versioning, testing, and component discovery (e.g., Storybook).
• Make thoughtful architectural decisions that enable accessibility, performance, consistency, and maintainability across LangChain’s UI stack.
• Improve UI build and test workflows: Optimize build performance, bundling strategy, and package versioning for the component library.
• Maintain tooling for testing and dependency management of the UI app.

What You'll Bring

• Extensive experience building modular, composable, and well-documented component libraries and/or design systems.
• Deep knowledge of React, TypeScript, HTML, and CSS.
• Familiarity with styling approaches (CSS Modules, CSS-in-JS, Tailwind, Sass, etc.) and design system tooling (Storybook, Chromatic, tokens pipelines, etc.).
• Experience collaborating closely with designers and non-engineering partners.
• Strong attention to detail, a high bar for craft, and genuine passion for accessibility and inclusive design.
• Familiarity with testing UI components and visual regression testing.