Frontend Developer

Onyx is building the consumer trading platform for the speculation economy- bringing prediction markets, sports, crypto, and real-world events into one seamless experience.

Following our Series A led by Payward, we’re growing the engineering team behind a fast, real-time consumer trading platform. We’re looking for a Frontend Developer / Mobile Engineer who can own the product across iOS, Android, or both - from architecture and development through testing, deployment, and ongoing performance.

This is a high-impact role for someone who has shipped polished consumer applications end to end and wants meaningful ownership over a core product experience.

What You’ll Do

• Build and ship mobile features using React Native and TypeScript
• Own development across iOS, Android, or both
• Work directly in Swift and/or Kotlin when native development is required
• Take applications and features from technical design through production release
• Manage testing, debugging, deployment, and App Store or Google Play submissions
• Integrate mobile applications with backend services and APIs operating in an AWS environment
• Improve application performance, reliability, responsiveness, and stability
• Build real-time, highly interactive product experiences
• Develop native integrations, reusable components, and scalable mobile architecture
• Collaborate closely with product, design, backend engineering, and infrastructure teams
• Monitor production issues and continuously improve the user experience

What We’re Looking For

• 2+ years of professional mobile engineering experience
• Strong experience with React Native and TypeScript
• Production experience with iOS, Android, or both
• Strong Swift experience for iOS and/or Kotlin experience for Android
• Experience deploying applications end to end through the App Store and/or Google Play
• Experience integrating mobile products with APIs and cloud-based systems, ideally in an AWS environment
• Strong understanding of mobile architecture, state management, testing, debugging, and release management
• Experience building polished, high-engagement consumer products
• Ability to work across React Native and native mobile code when needed
• Strong product judgment, attention to detail, and a high level of ownership
• Comfort working in a fast-moving startup environment
• Experience with real-time data, WebSockets, payments, trading, sports, gaming, animations, CI/CD, or performance-sensitive consumer applications is a plus.

Logistics

• Location: NoHo, New York City
• Schedule: Hybrid
• Compensation: $175,000–$250,000 in total cash compensation, plus equity
• Experience: 2+ years
• Work authorization: Candidates must already be authorized to work in the United States. Onyx cannot provide current or future visa sponsorship for this role.