Mobile App Engineer

Fullstack; New York, Northern (NY, KY); Hybrid; USD 120,000 - 180,000; Full time

Job summary

Fullstack in New York is seeking a mobile engineer to build the next generation trading app for finance. You will ship features for live market data, multi-venue execution, and real-time performance on iOS.

Collaborate across design, backend, and product, own modules from data handling to wallet integration, and ensure robust UX under volatility. You must be authorized to work in the United States.

Qualifications

• Production iOS experience with Swift in fintech or real-time data environments.
• Strong UI/UX sense and ability to wireframe and prototype.
• Experience shipping apps through the App Store and supporting full release cycles.
• Understanding of iOS performance, memory management, and background tasks.
• Experience with real-time data streams, WebSocket connections, and reconnection logic.

Responsibilities

• Build and maintain iOS features that stay responsive during market volatility.
• Develop a gesture-driven trading interface with information density for power users.
• Create high-performance charts and real-time data visualizations.
• Integrate with mobile wallets and on-device secure key management.
• Architect client-side state with REST APIs and WebSocket streams.
• Configure CI/CD pipelines for automated builds, previews, testing, and rollbacks.

Skills

iOS Development

Swift

Real-Time

UI/UX

WebSocket

Architecture

Ownership

Job description

The Role

As a Mobile Engineer at Fullstack, you will be part of building the next generation mobile trading app for the future of finance. This is a full featured trading experience, not a simplified pocket app. Features include live market data, complex order types, and multi venue execution on mobile. You will tackle challenges like maintaining synchronized real time price feeds, bringing the power of professional trading terminals to a mobile form factor, and building systems that perform under highly volatile market conditions.

What You’ll Build & Solve

iOS App Development: Design features that stay responsive during market volatility and handle real-time data efficiently.

Trading Interface: Build gesture driven mobile UI that delivers the information density of professional trading terminals without overwhelming small screens, while preserving full functionality for power users.

Data Visualization: Develop high-performance, interactive charts and real-time visualizations that help users make informed trading decisions.

Wallet Integration: Build native integrations with mobile wallets and biometric authentication. Handle transaction signing and secure key management on-device.

System Architecture: Integrate complex REST APIs and WebSocket streams while managing robust client-side cached state.

DevOps & Quality: Configure and maintain CI/CD pipelines for automated builds, previews, testing, and seamless rollbacks.

What You Bring

Production iOS Experience: 3+ years shipping iOS applications in Swift, ideally in fintech, trading, or real-time data environments.

Design Sensibility: Strong eye for UI/UX. Comfortable wireframing, prototyping, and making design decisions. Understand information hierarchy and gesture-driven interfaces.

App Store Experience: Shipped apps through the Apple App Store. Understand the full release cycle from provisioning to review to production.

Platform Knowledge: Deep understanding of iOS performance characteristics, memory management, and background processing.

Real-Time Systems: Experience building apps that handle live data streams. Know how to manage WebSocket connections, handle reconnection, and keep UI responsive.

Ownership Mindset: Comfortable making architectural decisions and leading feature development.

In-Person Collaborator: Thrive in high-bandwidth, in-person engineering environments.

Work Authorization: Must be authorized to work in the United States.