Software Engineer, Mobile

About Onyx.

Onyx is building the market for people who enjoy being right. Our consumer platform lets people take positions on what happens next across sports, prediction markets, crypto, financial markets, politics, culture, and real-world events.

More than one million users have already found Onyx, driving over $2 billion in monthly notional volume across our social sports platform. Now, we’re bringing that same energy into regulated financial markets through Onyx Predictions, a CFTC-registered introducing broker and NFA member.

In June 2026, we raised a $20 million Series A led by Payward, the parent company of Kraken, valuing Onyx at $220 million less than one year after emerging from beta. Our team comes from Jane Street, DraftKings, Robinhood, xAI, SIG, HRT, and Harvard.

We’re building Onyx in New York with a small team, serious momentum, and no interest in moving slowly. The product is live. The market is growing. The category is still ours to define.

The Role.

We’re hiring a Mobile Engineer to build the primary way customers experience Onyx.

Our mobile stack is primarily React Native, Expo, and TypeScript, supported by Node.js, PostgreSQL, AWS, and real-time data systems. You’ll work closely with product, design, backend engineering, data, and trading to build a mobile trading experience that feels fast, intuitive, and reliable - even when the markets aren’t.

This is not a role where you’ll maintain a small corner of an established application. You’ll own important product areas, influence our mobile architecture, and ship directly to a rapidly growing user base across iOS and Android.

Your work will be visible, your responsibilities will expand quickly, and you’ll have a meaningful voice in both the product and the future of mobile engineering at Onyx.

What You’ll Own:

• Build and ship customer-facing mobile features using React Native, Expo, and TypeScript.
• Own features across market discovery, trading, positions, balances, payments, and settlement.
• Build responsive experiences powered by live prices, market updates, and real-time activity.
• Own features from technical design through testing, release, monitoring, and iteration.
• Manage releases across the Apple App Store and Google Play Store.
• Improve application performance, reliability, stability, and overall health.
• Build reusable components and scalable mobile architecture.
• Integrate backend APIs, authentication, payments, analytics, push notifications, and third-party services.
• Partner with product and design to turn complex trading concepts into intuitive mobile experiences.
• Strengthen testing, deployment, CI/CD, and over-the-air update processes.

You’ll Do Well Here If You:

• Have 3+ years of professional mobile engineering experience.
• Are highly proficient in React Native, Expo, and TypeScript.
• Have shipped and maintained consumer applications across iOS and Android.
• Have managed App Store and Google Play submissions and production releases.
• Understand mobile architecture, performance, state management, and testing.
• Have experience with APIs, real-time data, authentication, and third-party SDKs.
• Can independently own complex features from idea through production.
• Move quickly while maintaining a high bar for quality and customer experience.

Even Better If You Have:

• Built mobile products in trading, crypto, payments, gaming, sportsbooks, or consumer fintech.
• Experience with WebSockets, live market data, or transaction-based applications.
• Familiarity with Swift or Kotlin.
• Experience with EAS Build, EAS Submit, Expo Updates, and mobile CI/CD.
• Worked with mobile security, biometrics, passkeys, wallets, or identity verification.
• Helped scale a high-frequency consumer application during rapid growth.

Location:

• This role is based in our NoHo, Manhattan office, with core in-office days Tuesday through Thursday.
• Candidates must be authorized to work in the United States. Onyx is unable to provide employment sponsorship for this position.

Compensation and Benefits: 

• The anticipated base salary range for this position is $150,000–$200,000, depending on experience, impact, and scope, plus a target bonus and equity. 

Benefits include:

• Fully covered medical, dental, and vision insurance.
• Meaningful equity ownership.
• Commuter benefits.
• A front-row seat to building a new category.

Why Onyx?

Onyx is for people with conviction.

We hire talented people, give them meaningful ownership, and expect them to use it. Our teams stay small, the work stays visible, and the distance between an idea and production stays short.

Onyx moves quickly because our markets move quickly. Titles matter less than judgment, initiative, and the quality of what you ship. Good ideas can come from anywhere, but the person willing to make the call is expected to follow it through.

We value people who are ambitious without ego, intellectually honest, comfortable with uncertainty, and energized by hard problems. We debate openly, decide quickly, and take responsibility for the result.

Come build what’s next with us.