Senior Frontend Platform Engineer, Design Systems

LangChain builds infrastructure and tools for developing production-grade AI applications. The Senior Frontend Platform Engineer will build and evolve the component library and UI quality systems, partnering with design and engineering teams to support consistent, accessible, and maintainable product interfaces.

Responsibilities:

• 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, dependency management of the UI app

Requirements:

• 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 toolings (Storybook, Chromatic, tokens pipelines, etc.)
• Experience collaborating closely with designers and non-engineering partners
• Strong attention to detail and a high bar for craft and genuine passion for accessibility and inclusive design
• Familiarity with testing UI components and visual regression testing