Senior Full-Stack Mobile Developer (React Native)

We are a small, funded product team taking a live iOS and Android app (React Native) into its most important release. The app is moving from a manual tool to an intelligent, automated daily companion. We are hiring one senior developer to own both the front-end experience and the back-end intelligence layer, and to help us make the key architecture decisions for what comes next. Full product details are shared under NDA. This post is about the bar we need you to clear, so read the application instructions carefully. The One Thing That Matters Most You have personally built and shipped cross-platform mobile apps that real users have in their hands today. Not prototypes, not tutorials, not apps that stalled before launch. We want to see them, use them, and hear exactly what you built. Everything below matters, but nothing matters more than proof that you have taken a mobile app all the way to the App Store and Google Play and kept it running. What You Will Own Front end A polished, animated experience: onboarding flows, sequenced screens, and a completion moment that has to feel premium. We care about craft and detail, not just functional screens. Back end Data modeling, serverless functions, a per-user scheduled notification engine, third-party AI API integration, subscription entitlement logic, and a time-series scoring system. Our current stack runs on Firebase, so you will work in it from day one, but part of your job is to tell us where it should go next. Your first deliverables In your first 1-2 weeks, before heavy building starts, you will: Review our functional spec (FSD) and write the technical spec (TSD) for how you will build it Give us your own build estimate and milestone plan against the October 31, 2026 target. Deliver a written backend recommendation: stay on our current stack, extend it, or migrate. For the backend call, weigh Firebase/Firestore, Postgres (for example Supabase), and other options against our real needs: 10,000+ active users, AI API integration, offline-first sync, reliable push at scale, velocity, and cost. We want an objective read from someone who has shipped on more than one backend, not someone married to a single tool. What You Must Have 3+ years building React Native apps that are live in production on both iOS and Android. Shipped and maintained, not just started. Strong full-stack backend fundamentals: serverless/cloud functions, data modeling, auth, security rules or access control, and API design. Hands-on experience with both a NoSQL database (for example Firestore) and a relational database (Postgres or similar). You should be able to reason about the trade-offs, because you will be advising us on exactly that. Production experience integrating a third-party AI API (Claude, OpenAI, or comparable), including handling latency, cost, and structured output. Proficient in TypeScript. Our codebase is TypeScript. RevenueCat for subscription entitlement management. It is already integrated in our codebase. Push notification infrastructure and scheduled/triggered server logic that runs reliably per user. Clear written English and comfort working async-first over Slack, with GitHub-based code review. Strong Advantage (Not Required) If you have shipped these before, tell us. If not, we expect a strong engineer to pick them up quickly. Firebase at real scale in production: Firestore schema design, Cloud Functions with complex triggers, FCM, and Firebase Auth. UX/UI craft: polished animation work such as SVG stroke animation, radial gradients, and staggered/sequenced motion. Device-native speech-to-text on iOS and Android. Anthropic Claude API specifics: prompt caching, system-prompt engineering, structured output. Experience scaling a consumer or wellness/subscription app to 10,000+ active users. Engagement Time commitment: we expect roughly 20+ hours per week, sustained. This is a real ongoing engagement, not a few hours here and there. Timeline: our v3 release targets October 2026. Expect focused, steady delivery between now and then, with the backend recommendation done in your first few weeks so we can lock the architecture early. Scope: substantial multi-month build with strong potential to continue into v3+ if it is a good fit. We would rather find one reliable partner for the long haul than churn through contractors. Tooling: GitHub, Slack for daily communication, TestFlight for iOS builds. Contract, hourly or fixed-price per sprint. Your preference. Tell us your rate and preferred structure. All builds, schema changes, and deployments are reviewed before release. We commit to a 48-hour feedback turnaround. How to Apply — Read Carefully You must submit a portfolio website or a link to your work before any screening call. Applications without a portfolio link will not be reviewed and will not receive a call. To be considered, include all of the following: A portfolio or work link (required, no exceptions). Applications without one will not be reviewed. One shipped mobile app you are proud of, live on iOS and/or Android, with a store link or video. Tell us specifically what you built. One backend system or serverless function you built. Describe the scale, the data model, and the hardest problem you solved. One example of UI craft or complex interaction, with the visible result (link, video, or GIF). Your one-paragraph read on the backend question: given the needs above, would you stay, extend, or migrate, and why? A confident “it depends, here is how I would decide” is a great answer. A brief note on how you approach scoping and estimating a build like this. We do not expect a number before you have seen the spec, but we want to see how you think about it. Your rate, preferred engagement structure, and realistic start date. How many hours per week you can realistically commit, sustained, between now and an October 31, 2026 v3 target. Be honest. We would rather know your real capacity up front. We respond to every complete application. We are looking for a developer who takes their craft seriously.