Software Engineer, Full-Stack

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, Draft Kings, 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.

We’re hiring a Full-Stack Software Engineer to build the systems and consumer experiences at the center of Onyx.

Our stack is primarily Type Script, React, React Native, Node.js, PostgreSQL, and AWS. You’ll work across it, building customer-facing trading experiences, backend financial infrastructure, real-time systems, and the services that keep everything moving.

This is not a role where you’ll spend months working on one narrowly defined component. You’ll own projects from the initial idea through production, work directly with product, design, trading, and operations, and make technical decisions that shape both the platform and its architecture.

Your work will be visible. Your responsibilities will expand quickly. You’ll ship directly to users and own what happens next.

• Build and ship full-stack product features using Type Script, React, and Node.js.
• Develop customer-facing trading experiences across web and mobile.
• Build backend services supporting markets, orders, execution, positions, balances, and settlement.
• Design reliable APIs, real-time systems, and scalable PostgreSQL workflows.
• Build and maintain production infrastructure in AWS.
• Integrate with exchanges, liquidity providers, payment systems, and financial partners.
• Improve system performance, observability, reliability, and fault tolerance.
• Partner with product, design, trading, and operations from concept through launch.
• Make consequential technical decisions and own the outcomes.

• Have 3+ years of professional software engineering experience.
• Are highly proficient in Type Script, React, and Node.js.
• Have built and maintained production applications across the stack.
• Understand relational databases, transactions, concurrency, and data consistency.
• Have production experience with PostgreSQL and AWS.
• Are comfortable building real-time, concurrent, or event-driven systems.
• Can move between frontend, backend, and infrastructure based on product needs.
• Independently lead technical projects from planning through production.
• Move quickly while maintaining a high bar for quality, reliability, and customer experience.

• Experience with React Native or Expo.
• Built products in trading, crypto, payments, prediction markets, or consumer fintech.
• Worked with Web Sockets, live data feeds, streaming systems, or event-driven architecture.
• Experience with order management, execution, market data, settlement, or broker connectivity.
• Helped scale a consumer application through rapid growth.

• This role is based in our No
  
  Ho, 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.

• The…