Senior Frontend Engineer

About JuiceX JuiceX is a rapidly growing prediction markets exchange. Our company is building the infrastructure to offer a fully compliant, transparent, and innovative marketplace for event driven contracts under U.S. regulatory frameworks. The Opportunity We are hiring a Senior Frontend Engineer to build and own the trading interface for JuiceX's Exchange. This is the surface where participants place trades, monitor positions, and react to live market data in real time, where a stale number or a dropped update carries real financial consequences. You will own the entire front end experience: real time state, performance, testing, and the component and design systems that keep a fast growing UI coherent. You will work closely with Product, Design, Market Operations, and the platform and engineering teams to turn complex market data into an interface that is fast, accurate, and trustworthy. Professional Experience Deep experience with TypeScript and modern React (hooks, concurrent rendering, Suspense), writing React 19 and clean strict mode code by habit Experience shipping and maintaining real time UIs (WebSockets, streaming state, backpressure, reconnection, and stale data handling), not just request/response CRUD Testing is native to how you work across unit, integration, and end to end layers, with a clear sense of which layer earns its keep Comfortable in a large monorepo, with strong judgment on module boundaries, shared packages, and why a leaky export is a design failure Design systems work, including tokens, theming, parity between Figma and code, and keeping a component library honest as it grows Experience with trading, markets, or fintech domains Qualifications 5+ years building and maintaining production web applications, with demonstrated senior level ownership Proven experience delivering real time, data intensive interfaces in production Hands on experience with end to end testing frameworks, including Playwright Experience operating within a large monorepo and a shared component architecture Charting at scale (Lightweight Charts, D3, canvas rendering) Accessibility in practice (WCAG) on dense, data heavy screens Preferred: SSR or edge rendering (Astro, Next, Remix) and web performance work Preferred: experience with, or informed opinions on when to avoid, micro frontend architecture Position Responsibilities Build and own the web trading interface, including real time market data, order entry, and position monitoring Design and maintain streaming state architecture (WebSocket connections, reconnection, backpressure, and stale data detection) for a reliable live UI Establish and maintain testing across unit, integration, and end to end layers, including Playwright coverage of critical trading flows Maintain clean module boundaries and shared packages within the monorepo Build and evolve the design system and component library, keeping parity between Figma and code as the product grows Optimize front end performance and responsiveness on dense, data heavy screens Ensure accessibility (WCAG) across the trading interface Partner with Product, Design, Market Operations, and platform and engineering teams to translate market data and workflows into accurate interfaces Uphold engineering rigor by verifying behavior, reviewing for correctness, and treating UI errors as high consequence