Senior Frontend Engineer - Design Systems

About the role

This role focuses on developing and maintaining the foundational elements of Mercury's product interface, including UI components, design tokens, and layout systems. The engineer will ensure these elements meet high standards for accessibility, performance, and visual precision. A key aspect of the work involves close collaboration with design partners, translating new design concepts into production-ready UI patterns and streamlining the development process for product teams.

The Senior Frontend Engineer will lead initiatives to introduce new UI patterns that address specific challenges faced by product teams, aiming to accelerate their ability to deliver improved user experiences. This includes exploring how AI can be integrated into the design system to create more leveraged outcomes and enhance the prototyping experience for designers. The goal is to enable rapid iteration and exploration of new concepts.

Success in this position means not only delivering robust and scalable design system components but also elevating the overall technical and AI proficiency of the team. This involves mentoring colleagues and establishing clear best practices. The ideal candidate will apply first-principles thinking to system design, always orienting their efforts toward achieving tangible outcomes that benefit multiple product teams.

The base salary for US employees ranges from $166,600 to $208,300, with Canadian employees having a separate range in CAD.

Skills that matter here

• React: This role requires deep experience with React for building and maintaining UI components within the design system.
• TypeScript: Proficiency in TypeScript is essential for developing robust and type-safe components and patterns.
• modern web technologies: A strong understanding of modern web technologies is necessary to ensure the design system is current and performant.

Who this role suits

• A developer with at least four years of frontend experience, specifically in building or maintaining design systems or shared component libraries.
• Someone who possesses a thorough command of modern frontend tooling, including build systems, CI/CD, and testing practices.
• An individual who demonstrates high agency, can create clarity in ambiguous situations, and applies first-principles thinking to problem-solving.
• A candidate with strong product taste and an instinct for creating leveraged solutions that benefit multiple teams, rather than isolated components.

From the employer

Responsibilities

• Build and maintain the components, patterns, and foundations (tokens, type, color, layout) that Mercury's product is woven from, holding a high bar for accessibility, performance, and pixel-level craft.
• Work hand-in-hand with design partners to bring new patterns from concept to production, tightening the loop between ideation and what actually ships.
• Lead projects that ship new UI patterns to solve real pain points for product teams, helping them build better experiences faster.
• Develop a design system that's as ready for AI as it is for people, applying the technology to create leveraged outcomes.
• Invest in the design system's prototyping experience, shaping the next iteration of how our design function rapidly prototypes, iterates on the product, and explores new concepts.
• Raise the craft and AI fluency of the people around you, through mentorship and clear best practices.

Requirements

• 4+ years of frontend development, with deep experience in React, TypeScript, and modern web technologies.
• Experience building or maintaining a design system or shared component library.
• A thorough command of modern frontend tooling: build systems, CI/CD, and testing.
• High agency, and comfort creating clarity in ambiguous spaces.
• First-principles systems thinking that stays oriented to outcomes.
• Strong product taste, and an instinct for leverage: the change that makes many teams better, not the one component polished in isolation.
• Hands-on fluency at the intersection of AI and software development.

Conditions

• Base salary: $166,600 - $208,300 for US employees.
• Base salary: CAD 157,400 - 196,800 for Canadian employees.
• Equity (stock options/RSUs) and benefits.
• Mercury values diversity & belonging and is proud to be an Equal Employment Opportunity employer.