Senior Back End Developer Jobs in Miami, FL (NOW HIRING)

Gemini is a global crypto and Web3 platform founded by Cameron and Tyler Winklevoss in 2014, offering a wide range of simple, reliable, and secure crypto products and services to individuals and institutions in over 70 countries. Our mission is to unlock the next era of financial, creative, and personal freedom by providing trusted access to the decentralized future. We envision a world where crypto reshapes the global financial system, internet, and money to create greater choice, independence, and opportunity for all — bridging traditional finance with the emerging cryptoeconomy in a way that is more open, fair, and secure. As a publicly traded company, Gemini is poised to accelerate this vision with greater scale, reach, and impact.

As a Senior Mobile Engineer on the Predictions team, you'll own the mobile experience for Gemini's CFTC-regulated prediction markets exchange. You'll build and ship trading interfaces for event contracts — from order entry and position management to real‑time market data — within Gemini's React Native app. You'll work closely with product, design, backend, and compliance to bring new contract types (binary, range, combo) to market on mobile and drive activation and retention for a fast‑growing product line.

• Build and maintain the Predictions mobile trading experience end‑to‑end: market browsing, order placement, portfolio views, and settlement flows.
• Architect performant, real‑time UI for streaming market data (orderbook, price charts, position P&L) using modern React Native patterns (TurboModules, JSI, native navigator integration).
• Collaborate with backend engineers on gRPC and WebSocket integrations that power live trading surfaces.
• Create reusable, well‑tested UI components shared across Predictions and the broader Gemini mobile app.
• Partner with product and design to shape mobile‑specific UX for new contract categories (weather, economics, crypto, sports) and features like combo contracts and range contracts.
• Scope and implement solutions independently, making informed architecture decisions and trade‑offs around native vs. JS boundaries.
• Establish and improve mobile development processes — testing strategy, release quality gates, OTA vs. native release decisions.
• Conduct thorough code reviews and mentor other engineers on React Native best practices.
• Use analytics and experimentation data to inform product and engineering decisions around activation funnels, onboarding, and trading engagement.

• 6+ years of software engineering experience, including 4+ years building production mobile applications with React Native.
• Strong proficiency in TypeScript.
• Deep understanding of React Native internals — bridging, native modules, performance profiling, and debugging.
• Experience building real‑time, data‑intensive UIs (trading, dashboards, live feeds).
• Strong UX/UI sensibility with a track record of contributing to design and product decisions, not just implementing specs.
• Expertise in unit and integration testing for mobile.
• Comfort working in a regulated environment where changes require rigor and auditability.

• Experience with financial or trading applications (orderbooks, charting, position management).
• Familiarity with Expo, EAS, and OTA update strategies.
• Experience with native module authoring (Swift/Kotlin) or SwiftUI/Jetpack Compose embedding via Expo Modules API.
• Exposure to gRPC, WebSockets, or similar real‑time transport protocols.
• Experience with performance analysis tooling (Flipper, React DevTools profiler, native instruments).
• Prior work at a fintech, exchange, or other regulated product environment.

The compensation & benefits package for this role includes:

• Competitive starting pay
• A discretionary annual bonus
• Long‑term incentive in the form of a new hire equity grant
• Comprehensive health plans
• 401K with company matching
• Paid Parental Leave
• Flexible time off

Salary Range: The base salary range for this role is between $140,000 - $200,000 in the State of New York, the State of California and the State of Washington. This range is not inclusive of our discretionary bonus or equity package. When determining a candidate’s compensation, we consider a number of factors including skillset, experience, job scope, and current market data.

In the United States, we offer a hybrid work approach at our hub offices, balancing the benefits of in‑person collaboration with the flexibility of remote work. Expectations may vary by location and role, so candidates are encouraged to connect with their recruiter to learn more about the specific policy for the role. Employees who do not live near one of our hubs are part of our remote workforce.

At Gemini, we strive to build diverse teams that reflect the people we want to empower through our products, and we are committed to equal employment opportunity regardless of race, color, ancestry, religion, sex, national origin, sexual orientation, age, citizenship, marital status, disability, gender identity, or Veteran status. Equal Opportunity is the Law, and Gemini is proud to be an equal opportunity workplace. If you have a specific need that requires accommodation, please let a member of the People Team know.