At Underdog, we make sports more fun. Our thesis is simple: build the best products and we’ll build the biggest company in the space, because there’s so much more to be built for sports fans. We’re just over five years in, and we’re one of the fastest-growing sports companies ever, most recently valued at $1.3B. And it’s still the early days. We’ve built and scaled multiple games and products across fantasy sports, sports betting, and prediction markets, all united in one seamless, simple, easy to use, intuitive and fun app. Underdog isn’t for everyone. One of our core values is give a sht. The people who win here are the ones who care, push, and perform. If that’s you, come join us. Winning as an Underdog is more fun. This role focuses on how the app feels as much as how it functions. It is one of the few engineering roles in which motion, interaction quality, and visual clarity are primary responsibilities. The person in this role will define how we use animation across the iOS app, help express our brand through movement, and support product teams in building polished, scalable experiences. About the role You will join the Mobile Platform team and work within a group focused on foundational mobile capabilities. Collaborate with other iOS and Android engineers, as well as product and design partners, to raise the quality of motion and interaction across the app. Design and build animations, transitions, and interactive UI components in SwiftUI, Lottie, and Rive. Work closely with designers to explore ideas quickly and turn the best ones into production-ready patterns. Help teams evaluate motion concepts, understand trade-offs, and use animation to improve clarity and engagement. Bring other engineers along as a key part of the role. Document patterns, create examples, pair with engineers when needed, and help the organization understand when and how to use motion responsibly. Build systems that enable product teams to ship polished interactions without relying on bespoke implementations. Who you are You are an experienced iOS engineer who cares deeply about how interfaces feel, not just how they function. You have a portfolio or examples of past motion or interaction work, and can explain the intent, decisions, and tradeoffs behind them. You understand animation tools such as SwiftUI animations, Lottie, and Rive, and know when to use each. You know how to build animations that perform well under real product conditions and how to debug issues that affect responsiveness. You work well with designers and can translate motion concepts into clear engineering plans. You communicate clearly with engineers, designers, and product partners and can guide conversations about what motion adds and what it costs. You are comfortable iterating quickly during exploration and being disciplined when shipping to production. You notice gaps in polish and take initiative to improve them without needing direction.