Senior Mobile Engineer

Role Overview

As a Senior Mobile Engineer at Topstep, you will help build the company’s mobile trading platform using React Native. You’ll lead the initial MVP build, define scalable mobile architecture patterns, and then embed within feature teams to drive ongoing mobile development.

Responsibilities

• Lead the mobile MVP effort from scratch using React Native, integrating with GraphQL APIs across trader and trading experience platforms.
• Establish reusable engineering patterns (components, custom hooks, TypeScript patterns, and testing strategies) that other engineers can adopt.
• Own end-to-end mobile features from design through App Store and Play Store releases, ensuring seamless backend integration and strong performance.
• Partner with product and design to translate trader needs into mobile experiences balancing UX with technical constraints.
• Embed quality and performance practices in every feature (testing, monitoring, crash reporting, performance optimization).
• After MVP launch, embed within feature teams to drive continued mobile development in cross-functional squads.
• Mentor engineers on React Native best practices, mobile architecture, and production ownership.
• Champion mobile-first thinking across the organization.

Required Qualifications

• 5+ years building production mobile applications with impact scaling patterns/practices across teams.
• Deep React Native expertise, including:
  • React Navigation
  • State management: Redux, Zustand, Context
  • Native module integration
  • Performance optimization
• Strong TypeScript and modern JavaScript fundamentals (React patterns, hooks, composition, functional programming concepts).
• Cross-platform mobile delivery to iOS App Store and Google Play Store.
• GraphQL client integration experience with Apollo Client (cache management, optimistic updates, error handling).
• Strong database fundamentals (e.g., PostgreSQL or SQL Server schema design, migrations, indexing, query optimization).
• Mobile performance optimization knowledge (bundle size, startup time, memory management, list virtualization, image optimization).
• Production app experience including crash reporting (e.g., Sentry, Crashlytics), analytics, remote config, and debugging production issues.
• Testing mindset and experience with:
  • Jest (unit tests)
  • Integration tests
  • E2E tests such as Detox and Appium
• Understanding of mobile CI/CD (automated builds, code signing, distribution, and release management).
• Demonstrated technical leadership via architectural documentation and code reviews; able to build component libraries/patterns.