Senior Software Engineer - Mobile

Human Interest is on a mission to ensure that people in all lines of work have access to retirement benefits. More than half of all working Americans are not saving enough for their future. Too often, it’s because they are employed by a company that doesn’t offer a retirement plan. Human Interest is changing that by making it affordable and accessible for small and medium-sized businesses to offer employees a path to financial independence through retirement savings. We’re a high-growth fintech company changing the retirement industry. We are backed by a number of investors. This includes funding from Marshall Wace and Baillie Gifford, as well as top investors such as BlackRock , TPG (The Rise Fund) , SoftBank, Glynn Capital , NewView Capital, USVP, Wing, Uncork, and more. About the role This is a high-impact, hands-on engineering role building the future of our mobile app experience. As a Senior Software Engineer on our Mobile team, you will design, build, and ship the features millions of employees and plan administrators rely on to manage their financial future, and help set the technical foundation for mobile engineering at Human Interest. The team's scope is broad, spanning multi-persona mobile experiences, native and cross-platform architecture, and release operations. This is a rare greenfield opportunity. As one of the founding engineers on a team built from the ground up, you will have a blank slate: pipelines, release process, QA, telemetry, and the native-vs-cross-platform architecture do not exist yet, so nothing is constrained by legacy decisions. You will ship the earliest versions, shape the patterns the team adopts, and partner with your engineering manager, Product, and Design, owning the outcomes that matter: app store ratings, crash-free sessions, and reliable delivery. This role is about leveraging AI to build. Operating as the architect and decision-maker, you will direct AI coding agents across the development lifecycle and help shape the team's agentic workflows, pairing that speed with an app that is fast, secure, accessible, and built to last. What you get to do every day • Build a polished experience across iOS and Android, native or cross-platform, that helps employees understand and grow their retirement savings, plus future experiences for 401(k) plan admins to manage plans on the go. • Architect a modern, modular codebase from scratch, with modern concurrency, clean dependency management, and testability at its core, and no legacy constraints. • Use AI coding agents as a core part of how you build, directing them across the development lifecycle as the architect and decision-maker and helping shape the team's agentic workflows and quality bar. • Solve hard fintech problems on mobile: accurate, real-time balances, secure authentication and biometrics, and protecting sensitive financial data. • Own how we ship: CI/CD, phased App Store and Play Store rollouts, feature flags, and automated UI testing, with crash-free rates and app ratings as your scoreboard. • Sweat the details with Design, from animations and haptics to data visualization and accessibility, so saving for retirement feels as good as any consumer app. • Partner with backend engineers on API contracts and backend-driven UI, and help define our native and cross-platform direction. What you bring to the role Experience • 5+ years of experience building and maintaining software in production, including shipping and owning consumer mobile apps through many App Store and Play Store release cycles. • Deep expertise in native mobile development (Swift and SwiftUI, or Kotlin and Jetpack Compose) or cross-platform frameworks (React Native, Flutter, Kotlin Multiplatform), with strong opinions on app architecture, performance, and te