Senior Flutter Engineer — Secure Storage & Offline Data Transfer

Senior Flutter Engineer — Secure Storage & Offline Data Transfer **About the Project** We're building a security-focused Flutter app (iOS & Android) that transfers and stores sensitive data offline via Bluetooth and Wi-Fi direct. The codebase is in active development and approaching deployment. You'll be coming in at a senior level with a clear path to lead engineer if the initial engagement goes well. **Initial Scope** Your first task will be implementing an append-only transaction ledger by modifying the current mutable one: an encrypted, device-resident log where every action creates a new entry and nothing is ever modified or deleted. Think of it as a tamper-evident audit trail. This is a self-contained, well-defined piece of work that will show us how you approach architecture, cryptographic storage, and clean Dart/Flutter code. If that goes well, the engagement expands to owning the full path to App Store and Google Play deployment — and potentially remaining on for post-launch support. **Stack** Flutter · Dart · Hive · flutter_secure_storage · Riverpod · iOS Keychain / Android Keystore · BLE · Wi-Fi Direct --- **To Be Considered — Required in Your Application** Generic proposals will not be reviewed. Please provide both of the following: 1. **A live app you contributed to** — a link downloadable today on both the App Store and Google Play. Finance, payments, banking, security, or data transfer apps strongly preferred. 2. **Proof you built it** — one or more of: your name in the store listing, a LinkedIn profile showing the employer or client, a GitHub commit history on a public repo, or a prior Upwork contract tied to that product. --- **You're a Fit If** - You've shipped a Flutter app with 10k+ downloads to both platforms - You've handled encrypted local storage in a production app - You've worked with BLE or Wi-Fi direct in Flutter - You're comfortable owning architecture and making decisions independently - You've navigated App Store and Google Play submission, review, and release **Engagement** Fixed-price initial task, with a strong likelihood of expanding to a longer-term lead role through deployment and beyond. Rate negotiable based on experience.