Lead Software Engineer - ReactJS Typescript

Job Description

We have an opportunity to impact your career and provide an adventure where you can push the limits of whats possible.

As a Lead Software Engineer at JPMorgan Chase within the Commercial & Investment Banks Margin & Collateral Technology team you’ll lead a team building modern React.js applications while maintaining and evolving existing Ext JS modules. A core part of the role will be planning and executing a pragmatic migration path from Ext JS to React—balancing stability, performance, accessibility, and developer experience.

Job Responsibilities

• Define front-end architecture, coding standards, and best practices across React and Ext JS codebases.
• Drive the roadmap for migrating legacy Ext JS features to modern React implementations.
• Conduct design and code reviews; mentor engineers and elevate the team’s craft.
• Optimize performance (memoization, virtualization, bundle splitting, caching) and run audits with Lighthouse.
• Ensure robust test coverage with Jest and React Testing Library; enable e2e tests via Cypress or Playwright.
• Manage builds and theming via Sencha Cmd and SASS; improve performance and stability of legacy features.
• Implement bridging strategies (embedding React within Ext JS or vice versa) to enable incremental migration.
• Partner with Product and Design to deliver responsive, WCAG 2.1 AA-compliant experiences
• Work closely with backend teams on REST/GraphQL integration, WebSockets, and API contracts.
• Translate product goals into technical plans; break down work and drive predictable delivery in Agile sprints.
  
  

• Formal training or certification on software engineering concepts and 5+ years applied experience
• 10+ years of front-end development experience, with 3+ years in a tech lead or staff-level role.
• Deep expertise in React.js and TypeScript building large-scale, production-grade applications.
• Hands-on experience with Ext JS (6.x/7.x), Sencha Cmd, theming, and performance optimization.
• Proven track record migrating legacy front ends (preferably Ext JS) to React, including micro-frontend patterns.
• Strong proficiency with modern tooling: Webpack or Vite, Node.js, npm/yarn, Git, ESLint, Prettier.
• Solid understanding of accessibility, responsive design, and internationalization.
• Experience with automated testing across unit, integration, and e2e levels.
• Familiarity with RESTful APIs, GraphQL, and client-side performance profiling.
  
  

• Next.js (SSR/SSG), design system creation, and token-based theming.
• Data visualization (D3, Highcharts, Recharts).
• Monorepo tooling (Nx, Turborepo), micro frontends, module federation.
• Observability in the front end (logging, metrics, tracing) and bundle analysis.
• Experience in regulated or enterprise environments