Senior Software Engineer, Backend

About Sleeper Sleeper is on a mission to connect people over sports through games and community. As one of the fastest-growing platforms in the fantasy sports and real-money gaming space, we're redefining how sports fans engage—whether it's through season-long leagues, pick'em contests, or real-time interactions with friends. Our team is lean, passionate, and product-driven. We obsess over user experience and believe that building delightful, fast, and reliable products is the best way to grow. Backed by some of the most respected investors in Silicon Valley, including Andreessen Horowitz and General Catalyst, we're building the future of sports engagement. About the Role We're looking for a Senior Software Engineer - Backend to help us scale the core systems behind our fantasy sports and DFS (Daily Fantasy Sports) offerings. In this role, you'll build and own critical backend services, and collaborate with fellow engineers as we scale to support tens of millions of passionate sports fans. You'll collaborate cross-functionally to bring innovative features to life—from real-time contest engines and game logic to personalized content and secure, seamless payments. You'll own significant parts of the backend stack and help raise the bar for performance, scalability, and reliability at Sleeper. What You'll Do Design and build core backend systems that power Sleeper's games and real-time user experiences—fantasy contests, Sleeper Picks, user profiles, leaderboards, and more. Build scalable, distributed systems capable of handling millions of concurrent users with low latency and high availability. Own backend initiatives from concept to deployment, ensuring clean interfaces, well-documented services, and resilient infrastructure. Optimize system performance and proactively address bottlenecks through monitoring, profiling, and capacity planning. Collaborate cross-functionally with product, design, and frontend teams to deliver features that users love. Contribute thoughtful code reviews and help strengthen backend engineering best practices and standards. Who You Are 5+ years of backend software engineering experience. Proven ability to build and scale distributed systems that serve millions of users in real-time or gaming environments. Strong proficiency in one or more backend languages (e.g., Go, Python, Node.js, Java), and an understanding of trade-offs between them. Solid knowledge of databases (both SQL and NoSQL), caching strategies, and message queues (e.g., Kafka, RabbitMQ, Pub/Sub). Comfortable designing and maintaining RESTful and/or graphql APIs, data models, and internal tooling. Cloud experience (AWS, GCP, or similar), with familiarity with containers (Docker) and orchestration (Kubernetes a plus). Strong product mindset—you care about the why, not just the how, and you build with users in mind. Excellent communication and collaboration skills. Bonus: Proficiency in Elixir Bonus: Passion for sports, gaming, or building multiplayer or real-time systems. Why Join Sleeper? Massive Impact – Your work will touch millions of users and help shape the next generation of sports entertainment. High Ownership – We trust our engineers to make high-leverage decisions and drive meaningful outcomes. Startup Agility – Move fast, ship often, and see your work in the hands of users quickly. Culture-First Team – We're a team of builders, thinkers, and sports lovers who value humility, collaboration, and having fun along the way. What We Offer Competitive salary ($170,000–$220,000) /year not inclusive of stock options and benefits) Equity Comprehensive medical, dental, and vision insurance 401(k) Generous PTO and flexible remote work policy Opportunities for fast career growth in a high-impact role A small, focused team where your contributions truly matter