Senior Frontend Engineer

Responsibilities

• Build and maintain components, patterns, and foundations (tokens, type, color, layout) that Mercury's product is built from, maintaining a high bar for accessibility, performance, and pixel-level craft.
• 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.
• Thorough command of modern frontend tooling: build systems, CI/CD, and testing.
• High agency, and comfort creating clarity in ambiguous spaces. You take ownership and move without waiting for a defined path.
• First-principles systems thinking that stays oriented to outcomes. You make clear decisions that drive toward results instead of getting stuck in open questions.
• 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: a real command of how emerging AI paradigms are changing the way software gets built, and the ability to turn that into practical leverage, both for the design system itself and for the people who build on it.

Nice-to-Haves

• Experience with AI tools and paradigms in software development and design systems.