Sr. Design System Engineer

About the Team
The Design Foundations team is a small group of designers and engineers focused on improving the quality and efficiency of product design. We build the tools, practices, and processes used by all designers and front-end engineers across the organization. Our most established work includes two design systems: Interstate (for B2B products) and Iris (for consumer-facing products). More recently, we've been building AI tools like context packs, MCP tools, and Claude skills that deliver on our mission of quality and efficiency.
We're looking for a Senior Software Engineer to help build, evolve, and scale our design system: the shared foundation beneath every product UI we ship. You'll work at the intersection of design and engineering, building React and web components, managing design tokens, creating AI-powered tooling, and ensuring our system raises the quality bar across everything we build.
This isn't a role where you maintain a component library in isolation. You'll work closely with product designers, product engineers, and the broader organization to create tools, components, and infrastructure that make everyone around you faster and better. As AI-assisted development accelerates, the design system becomes the source of truth that ensures quality and consistency at scale, whether a component was composed by a person or an agent. This role sits at the center of that shift.
What You'll Do

• Build, maintain, and evolve a cross-platform design system spanning React components and web components, with thoughtful, composable APIs that prioritize developer ergonomics.
• Manage our design token architecture, from primitive values to semantic and component-level tokens, bridging Figma and code to ensure visual consistency across platforms.
• Build and utilize MCP tools, skills, AI agents, and internal tooling that leverage the design system to accelerate product development. Make the system machine-readable so AI can compose UIs using our components correctly.
• Create and maintain documentation, interactive playgrounds, and component showcases that make adoption effortless. Mentor engineers across the organization on design system best practices.
• Champion accessibility and infrastructure: automated a11y testing, WCAG compliance, CI/CD pipelines, visual regression testing, versioning, and release management.
• Collaborate deeply with product designers to bridge design intent and engineering implementation, contributing to the design process from ideation through production.

Who You Are
We care about the depth and quality of your experience more than years on a resume. That said, candidates who thrive in this role typically have 5+ years of frontend engineering experience. Direct design systems experience is a plus, not a prerequisite.

• Deep in TypeScript and React, including advanced patterns like compound components, headless UI, and controlled/uncontrolled APIs. Experience with (or strong interest in) web components and custom elements.
• Bachelor's degree in Computer Science or related discipline, and 4 years' experience in a related field. The right candidate could also have a different combination, such as a master's degree and 2 years' experience; a Ph.D. and up to 1 year of experience; or 16
  years' experience in a related field.
• A systems thinker. You've used component libraries, understood their constraints, and have opinions about what makes them good or bad. You naturally see patterns, design for reuse, and anticipate how your decisions cascade across a product.
• Familiar with design token tooling and workflows: Style Dictionary, Figma variables/tokens, token transforms, and the full pipeline from design to code.
• Accessible by default. Strong understanding of WCAG and hands-on experience testing for accessibility across browsers and assistive technologies.
• Fluent in AI-assisted development. You already use AI tools in your day-to-day work, whether that's MCP servers, LLM tooling, prompt engineering, or agent-based workflows. The playbook for "design systems + AI" is being written right now, and you want to help write it.
• Visually literate. You don't need to be a designer, but you understand typography, spacing, color, layout, and motion, and you have opinions about what makes software feel great.
• A clear communicator. Design systems work is fundamentally about advocacy, documentation, and helping others succeed. You can articulate complex technical concepts to both engineers and non-engineers.
• Obsessed with quality. You sweat the details: the border radius, the focus ring, the prop naming, the error state nobody thought to design. You believe a design system's job is to raise the floor for quality across the entire product.
• Biased toward shipping. You know when to polish and when to ship. You use every tool at your disposal, including AI, to move fast without sacrificing the quality your teammates depend on.
• Growth-oriented. You thrive in ambiguity and are energized by problems that don't have established solutions yet. You're just as excited to learn from your teammates as you are to teach them.
• Bachelor's degree (list any requirements of discipline here) and 4 years' experience in a related field. The right candidate could also have a different combination, such as a master's degree and 2 years' experience; a Ph.D. and up to 1 year of experience; or 16
  years' experience in a related field.

Nice to Haves:

• Experience with Figma plugin development or Code Connect.
• Contributions to open-source design systems or component libraries.
• Experience with monorepo tooling (Turborepo, Nx) for managing multi-package design system repositories.
• Familiarity with animation and motion design (Framer Motion, CSS animations, View Transitions API).
• Experience building Storybook or similar component documentation and testing platforms.
• Experience with MCP server development or integration.

What's In It For You
Here's a sneak peek of the benefits at your disposal as a Cox employee:

• A competitive salary and top-notch bonus/incentive plans.
• Exceptional work-life balance, flexible time-off policies and accommodating work schedules.
• Comprehensive healthcare, with multiple options for individuals and families.
• Generous 401(k) retirement plans with up to 8% company match.
• Mental health support, including counseling and access to virtual wellness resources such as CALM.
• Access to Care.com, with up to 10 days of subsidized care for children, seniors and pets.

Check out all our benefits.
USD 101,500.00 - 169,100.00 per year
Compensation:
Compensation includes a base salary in the range of $101,500.00 - $169,100.00. The base salary may vary within the anticipated base pay range based on factors such as the ultimate location of the position and the selected candidate's knowledge, skills, and abilities. Position may be eligible for additional compensation that may include an incentive program.
Benefits:
The Company offers eligible employees the flexibility to take as much vacation with pay as they deem consistent with their duties, the company's needs, and its obligations; seven paid holidays throughout the calendar year; and up to 160 hours of paid wellness annually for their own wellness or that of family members. Employees are also eligible for additional paid time off in the form of bereavement leave, time off to vote, jury duty leave, volunteer time off, military leave, and parental leave.
EOE, including disability/vets