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Fanatics Markets is a real-money prediction and trading platform where users invest in moments they care about—from sports and entertainment to political elections. This Senior Software Engineer III (Fullstack) role offers significant ownership over the web application that customers use to interact with the product.
You'll join a product at an exciting early stage, helping shape its evolution as core features are built, the platform scales, and technical foundations are refined. This is a senior individual contributor role with substantial technical leadership responsibilities.
Key responsibilities include:
- Lead design, development, testing, and deployment of scalable, high-quality web experiences using React, Next.js, and modern JavaScript/TypeScript
- Drive technical evolution of the Markets web platform in partnership with product and design teams
- Own features end-to-end: specification writing, implementation, instrumentation, deployment, monitoring, and iteration based on metrics
- Design and implement experimentation capabilities (feature flags, A/B tests) to validate ideas quickly and safely
- Integrate with backend APIs and collaborate with platform teams to build reliable, observable systems
- Make contributions to the Go backend as needed
- Conduct thorough code reviews and raise the bar on code quality, readability, and maintainability
- Leverage AI tools (Claude Code, Cursor, Codex, GitHub Copilot) to accelerate development velocity while maintaining high standards for security, correctness, and performance
- Establish and document team standards for AI usage, including prompt patterns, code review checklists, and validation strategies
- Contribute to a fast-paced 0→1 environment, unblocking others and taking initiative where processes are still being defined
Required qualifications:
- 4+ years building highly scalable, user-facing web applications using modern JavaScript/TypeScript and React
- Strong experience in React architecture, component-driven development, and modern state management patterns (NextJS, TanStack Query, Tailwind, Zustand)
- Familiarity with web3 libraries such as ethers.js, viem, or similar client libraries for smart contract interaction
- Deep knowledge of JavaScript/TypeScript language features, idioms, and best practices with ability to influence team standards
- Strong understanding of performance optimization, responsive design, accessibility, and web standards
- Experience integrating with backend APIs and collaborating with cross-functional platform/infrastructure teams
- Experience with CI/CD pipelines, testing strategies, and safe deployment practices
- Team-first mentality with willingness to do what it takes to get the job done
- Demonstrated experience using AI tools for code generation and development acceleration
