Senior Frontend Engineer - Mobile (Sleeper)
Posted on: December 16, 2025 | On-Site
Company Name: Sleeper.com | Department: Engineering
Division: Information Technology | Employment Type: Full-Time
Location: San Francisco Area, United States (Remote Available)
Schedule: On-Site (Office-Centric) | Experience Level: 5+ Years
About Sleeper: Building the Future of Fantasy Sports
Sleeper stands as one of the most rapidly expanding platforms in the fantasy sports and gaming industry, fundamentally revolutionizing how millions of sports enthusiasts connect, compete, and engage with their favorite games. What began as a dedicated NFL fantasy football platform has evolved into a comprehensive sports gaming ecosystem spanning more than a decade of continuous innovation and expansion.
Our journey of over 10 years has been marked by strategic growth and diversification. Today, Sleeper offers fantasy experiences across multiple major sports leagues, including NFL, NBA, LCS (League of Legends Championship Series), and soccer, providing fans with year-round engagement opportunities across their favorite sports and esports competitions.
At the heart of our innovation is Sleeper Picks, our real-money Daily Fantasy Sports (DFS) game that represents the next generation of sports gaming. In Sleeper Picks, users engage in an exciting prediction-based format where they forecast player performance against projections provided by trusted third-party vendors. This unique approach combines the thrill of fantasy sports with accessible, engaging gameplay that appeals to both seasoned fantasy veterans and newcomers alike.
Our success and vision have attracted backing from some of Silicon Valley's most prestigious investors, positioning us at the absolute forefront of innovation in the sports gaming industry. This financial support enables us to push boundaries, experiment with cutting-edge technologies, and continuously enhance the user experience for our growing community of millions of dedicated users.
The Role: Senior Frontend Engineer (Mobile)
We are actively seeking an exceptionally intelligent and innovative Frontend Software Engineer to join our dynamic engineering team. At Sleeper, we hold a fundamental belief in the transformative power of smart, creative individuals to drive meaningful change and build extraordinary products. We don't simply look for candidates who check boxes on a list of technologies—we seek brilliant problem-solvers who can adapt, learn, and innovate regardless of their specific technical background.
As a Senior Frontend Engineer (Mobile) at Sleeper, you will assume a crucial role in developing, optimizing, and scaling our mobile and web products. Your work will directly impact millions of dedicated users every single day, ensuring our platforms deliver exceptional scalability, unwavering reliability, and uncompromising quality. You'll be working on products that users are passionate about, in an industry that's constantly evolving and presenting new challenges to solve.
Technical Environment
Our mobile platform is built on a modern, sophisticated technology stack centered around React Native, providing a seamless cross-platform experience for iOS and Android users. We've invested significantly in modernizing our codebase with TypeScript, bringing type safety, improved developer experience, and enhanced code maintainability to our entire mobile ecosystem.
We leverage many of the industry's leading packages and libraries, including:
- React Query for powerful server state management and data synchronization
- React Navigation for intuitive, performant navigation experiences
- Reanimated for fluid, 60fps animations that delight users
We're searching for an experienced developer who brings not just technical proficiency but also wisdom gained from building and scaling mobile applications. You'll have the opportunity to apply your knowledge and skills to help refine our product, introducing innovative new features, elevating quality standards, and delivering lightning-fast performance that exceeds user expectations.
Key Responsibilities
Collaborative Design and Technical Specification
You will work closely with our talented design team to deeply understand user requirements, pain points, and opportunities for innovation. Your role involves translating creative design concepts and user experience goals into detailed technical specifications that guide implementation. This requires strong communication skills, an eye for detail, and the ability to bridge the gap between design vision and technical reality.
Code Development and Quality
Write clean, maintainable, and efficient code using React Native, TypeScript, and our suite of related libraries including React Query, React Navigation, Reanimated, and others. Your code should exemplify best practices, be well-documented, and serve as a model for the team. You'll be expected to participate actively in code reviews, providing constructive feedback to peers while remaining open to suggestions for improving your own work.
Component Architecture and Reusability
Develop reusable UI components that form the building blocks of our application. Implement a well-structured component hierarchy that promotes code reuse, maintainability, and consistency across the application. Your architectural decisions will have lasting impact on development velocity and product quality, so thoughtful design and planning are essential.
Advanced React Implementation
Implement sophisticated user interface functionality and logic leveraging the full power of React features, including state management patterns, props drilling solutions, custom hooks, context API, lifecycle methods, and performance optimization techniques like memoization and lazy loading. You should be comfortable working with both class-based and functional components, understanding when each approach is most appropriate.
Backend Integration
Integrate front-end components seamlessly with back-end services using modern APIs, whether RESTful or GraphQL-based. You'll work closely with backend engineers to define API contracts, handle error states gracefully, implement proper loading states, and ensure data consistency across the application. Understanding of API design principles and best practices is important for effective collaboration.
Performance Optimization and Debugging
Troubleshoot and debug complex technical challenges including performance bottlenecks, socket connection issues, data caching strategies, memory leaks, and other advanced problems that arise in large-scale mobile applications. You should be proficient with debugging tools, performance profilers, and monitoring solutions to identify and resolve issues efficiently.
Continuous Learning and Innovation
Stay current with the latest advancements in React, React Native, mobile development best practices, accessibility guidelines (WCAG), and emerging technologies in the mobile space. Bring new ideas to the team, advocate for adopting beneficial technologies or practices, and help maintain Sleeper's position as an innovative leader in sports gaming technology.
Ideal Candidate Profile
Educational Background
A degree in Computer Science or equivalent practical experience in software engineering. We value both formal education and self-taught expertise, recognizing that brilliant engineers come from diverse educational backgrounds. What matters most is your ability to write excellent code and solve complex problems.
Professional Experience
You bring 5+ years of mobile and/or web development experience with a strong emphasis on frontend technologies. This experience should include working on production applications at scale, handling real users, and navigating the challenges that come with building consumer-facing products. Experience specifically with React Native is highly valuable but not absolutely required if you have deep React experience and mobile fundamentals.
Ownership and Leadership Mindset
You possess a genuine desire to take ownership of large-scale products, with the freedom and autonomy to design and develop best-in-class solutions. You're not someone who simply executes tickets—you think strategically about product direction, user experience, and technical architecture. You're comfortable making important decisions and standing behind them while remaining open to feedback and collaboration.
Technical Excellence
Proven ability to develop and implement sophisticated algorithms or systems in professional settings, demonstrated through previous work experience. You have strong coding skills in JavaScript (and ideally TypeScript), with deep knowledge of best practices, design patterns, testing strategies, and software craftsmanship principles. You write code that others enjoy reading and working with.
Entrepreneurial Spirit
Highly proactive with a documented track record of building processes, systems, or products from scratch. You possess the willingness and confidence to challenge traditional paradigms when appropriate, bringing fresh perspectives to established practices. You're not satisfied with "the way things have always been done" if there's a better approach waiting to be discovered.
Adaptability and Comfort with Ambiguity
Comfortable operating in fast-paced, sometimes ambiguous environments where requirements may evolve and priorities can shift. You thrive on innovation and embrace the challenge of creating something new rather than being intimidated by uncertainty. You can make forward progress even when you don't have all the answers, using your judgment and experience to navigate ambiguity effectively.
Collaboration and Communication
Strong collaboration skills with the ability to work effectively across disciplines—with designers, product managers, backend engineers, QA, and other stakeholders. You communicate technical concepts clearly to non-technical audiences and actively contribute to a positive, supportive team culture.
What Sleeper Offers
Competitive Compensation
A comprehensive salary range of $180,000 to $235,000 USD annually, determined based on your experience level, demonstrated skills, and the value you bring to the organization. This base salary is just the foundation of your total compensation.
Comprehensive Benefits Package
We provide a full suite of benefits designed to support your health, wellbeing, and financial future:
- Medical Insurance: Comprehensive health coverage to keep you and your family healthy
- Dental Insurance: Complete dental care coverage
- Paid Time Off (PTO): Generous vacation and personal time to rest and recharge
- 401(k) Retirement Plan: Plan for your future with our retirement savings program
Impactful Team Environment
Join a small, highly talented team where your contributions genuinely matter and are visible. You won't be lost in a massive organization—your work directly influences product direction, and your voice is heard in important decisions. Every team member plays a critical role in our success.
Industry Leadership Position
Be at the absolute forefront of transforming the sports betting and DFS landscape. Work on products that are shaping how millions of people experience fantasy sports. Your innovations today will influence how users engage with sports gaming for years to come.
Professional Growth and Development
Receive strong support for your professional growth within a company backed by leading Silicon Valley investors. Access to learning resources, conference attendance, mentorship opportunities, and the chance to work with cutting-edge technologies and solve fascinating technical challenges.
Mission-Driven Culture
Work on products you can be proud of, building experiences that bring joy and excitement to sports fans worldwide. Join a team that's passionate about what we build and committed to excellence in execution.
Application Process
If you're excited about this opportunity to join Sleeper and help shape the future of fantasy sports gaming, we'd love to hear from you. We're seeking engineers who are not only technically excellent but also passionate about building exceptional products and collaborating with talented teammates.
Sleeper is committed to building a diverse, inclusive team that reflects the communities we serve. We encourage applications from candidates of all backgrounds and experiences.
Ready to make an impact? Apply now to join the Sleeper team as our next Senior Frontend Engineer (Mobile).
Sleeper is an equal opportunity employer committed to diversity and inclusion in the workplace.
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