Senior Fintech Mobile & Backend Developer (React Native/Flutter + Node.js/Go)

About the Project We are a well-funded fintech startup building a next-generation financial platform. Our goal is to provide a seamless, highly secure, and intuitive mobile experience for our users to manage their finances, execute transfers, and track their financial health. We are looking for a Senior Full-Stack Mobile Developer (or a tight-knit boutique development team) to take ownership of building our MVP from the ground up. If you are passionate about clean architecture, bank-grade security, and building products that actually matter, we want to talk to you. What You Will Build (Initial MVP Scope) • Secure Onboarding & Auth: Biometric login, MFA, and secure session management. • Core Wallet & Ledger: Real-time account balances, double-entry ledger management, and digital wallet functionality. • Payment Rails & Integrations: Connecting with third-party banking APIs (e.g., Plaid), payment processors (Stripe/Dwolla), and handling webhooks. • Transaction Engine: Comprehensive transaction history, categorization, and reporting. • Admin/Operations Dashboard: A secure web-based portal for our internal team to manage users, monitor transactions, and handle support. • Bank-Grade Security: Implementation of encryption at rest/transit, fraud prevention logic, and compliance with standard financial security practices. Our Preferred Tech Stack (Open to your expert recommendations) • Mobile: React Native or Flutter (Cross-platform is required for MVP). • Backend: Node.js (NestJS/Express), Go, or Python. • Database: PostgreSQL (Strictly relational for financial data integrity). • Cloud/DevOps: AWS or GCP, Docker, CI/CD pipelines. Who You Are • You have 5+ years of experience in full-stack mobile development. • You have proven experience building fintech, banking, or crypto applications (you understand that in fintech, accuracy and security "moving fast and breaking things"). • You have deep experience integrating with financial APIs (Plaid, Stripe, Dwolla, etc.). • You write clean, well-documented, and testable code. • You are a proactive communicator who can push back on bad ideas and suggest better architectural solutions. How to Apply (Please Read Carefully) We receive many proposals. To ensure you have read this post, please start your proposal with the word "LEDGER". In your proposal, please include: 1. Portfolio: Links to 2-3 specific fintech or complex financial apps you have built. Briefly explain your specific role in each. 2. Tech Stack: Your recommended tech stack for this project and a brief explanation of why. 3. Engagement Model: Your hourly rate (and estimated weekly availability) OR your estimated fixed-price range for an MVP of this scope. 4. Architecture: A brief (2-3 sentence) summary of how you would handle state management and secure API communication between the mobile app and the backend. Note: We are open to hiring an exceptional individual freelancer or a small, highly coordinated agency. If applying as an agency, please detail the team structure.