Software Engineer II - Frontend - Pro - Infra

Kraken is a mission-focused company rooted in crypto values, seeking a Software Engineer II to join their Pro team. The role involves designing, developing, and maintaining features in a large multi-product React web application used by professional traders globally, while ensuring high performance and stability under load.

Responsibilities:

• Leverage LLM's to accelerate development while still producing production-ready code
• Leverage LLM's to build agentic flows to automate tasks and improve productivity
• Design, develop and maintain features in a large, multi-product React web application used by professional traders globally
• Own performance end to end: profile, measure and optimise real-time UI updates (tables, order books, charts, order forms) so the app stays responsive under heavy WebSocket throughput
• Build and evolve the WebSocket and Web Worker layer that powers live market data, balances, positions and order updates across the app
• Set the standard for high-quality code through reviews, mentorship and constructive feedback to engineers across the team
• Contribute to technical strategy: architecture, data flow, state management, component design and shared libraries used across the trading surfaces
• Safeguard performance improvements with regression-resistant patterns, instrumentation, dashboards and alerts, so wins do not silently erode over time
• Own observability for the features you ship: meaningful Sentry instrumentation, Mixpanel events, structured logs and actionable alerts
• Write integration and component tests
• Drive process improvements (engineering practices, tooling, build pipeline, AI-assisted workflows) and lead by example

Requirements:

• 4+ years of experience in software development, with a focus on production web applications
• Deep understanding of JavaScript/TypeScript and strong proficiency with the modern React ecosystem
• Experience building real-time UIs with WebSockets and Web Workers
• Strong React and JavaScript performance skills
• Experience working with LLM coding tools (Cursor, Claude, Copilot or similar) to accelerate development while still producing production-ready code
• Hands-on experience with React Query or similar
• Practical experience with production user monitoring and observability
• Experience with frontend testing at multiple levels
• Comfortable with feature flagging and progressive rollouts
• Familiarity with modern frontend build pipelines and tooling (rsbuild/webpack/SWC, monorepos, TypeScript project references, ESLint, Prettier, Husky)
• Strong understanding of UI/UX best practices and design-system driven development
• Experience within a large technology organization or fast-growing startup
• Strong written and verbal communication skills in English