Full-Stack Developer for AI Assistant App

Full-Stack Developer Needed — AI Assistant App for Brazilian Market (iOS, Android & Web) Project Overview We are looking for an experienced Full-Stack / Mobile App Developer or small development team to build and launch a modern AI assistant application specifically designed for the Brazilian market. The user experience will be similar to leading AI chat applications, but the product will have its own original name, branding, design, features, and identity. We are NOT looking to develop our own AI language model from scratch. We want to use established AI APIs and preferably start with a high-quality existing source-code framework/template to reduce development time and cost. If you already own or have experience with a commercially licensed AI chatbot framework that can be customized, please mention it in your proposal. Target Market 🇧🇷 Brazil The application should be designed primarily for Brazilian users, with: * Native Brazilian Portuguese (PT-BR) * Brazilian-friendly user experience * Prices displayed in Brazilian Real (R$) * Free and paid subscription options * Brazilian payment integration where possible, including PIX * Ability to expand with Brazil-specific AI tools and services Platforms The initial product should include: * iOS application * Android application * Responsive web application * Backend/API * Admin dashboard We are open to cross-platform technologies such as Flutter or React Native if this reduces development cost and makes maintenance easier. Core Features AI Chat * Modern conversational AI interface * Integration with established AI APIs * Streaming AI responses * Conversation history * Start/delete/rename conversations * Multiple AI models if appropriate * System prompts/custom AI personalities * Brazilian Portuguese optimized experience User Accounts * Email registration/login * Google/Apple login where appropriate * User profiles * Free and premium accounts * Usage limits * Password recovery * Account deletion AI Capabilities We would eventually like support for: * Text conversations * Voice input * AI voice responses * Image understanding * Image generation * PDF/document uploads * Document analysis * Camera/photo uploads Some advanced features can be Phase 2 if necessary. Payments We need subscription capabilities for Brazil, potentially including: * PIX * Credit/debit cards * Monthly subscriptions * Annual subscriptions * Free tier with usage limits * Premium tier Developer should recommend the best payment architecture while respecting Apple App Store and Google Play requirements. Admin Dashboard Administrators should be able to: * View/manage users * Suspend accounts * Manage subscription levels * Set AI usage limits * Monitor API usage * Monitor estimated AI costs * Manage AI models * Modify system prompts * View basic analytics * Manage plans/pricing * Send announcements Architecture & Security The application must be designed so that AI API keys and other private credentials are never exposed inside the mobile or web client. API requests should be handled securely through our backend. The system should also include reasonable protections against abuse and unexpectedly high API usage. IMPORTANT — Source Code & Ownership This is extremely important. Upon final payment, we require: * Complete source code * Mobile application source code * Web application source code * Backend source code * Database structure * Admin dashboard source code * Deployment/configuration documentation * Build instructions * Commercial rights to the custom work * All project files * All design files created for the project The application must be deployable using accounts owned and controlled by our company. We do not want to become permanently dependent on the original developer to operate the application. Any third-party/open-source/paid components used must be disclosed along with their licenses and recurring costs. Development Approach We strongly prefer NOT to reinvent technology that already exists. If you have a high-quality AI application framework or commercially licensed source code that can legally be customized, we are interested in using it. Our priority is: Reliable technology + excellent customization + fast development + reasonable cost. Milestone-Based Project We prefer milestone payments rather than paying the entire project upfront. Suggested milestones: Milestone 1 — Architecture & Working Prototype Basic UI, user accounts and functioning AI conversation. Milestone 2 — Backend & User System Database, conversation history, usage limits and admin foundation. Milestone 3 — Premium Features Subscriptions/payments, voice, files/images and additional AI capabilities. Milestone 4 — Brazilian Localization & UI Complete PT-BR localization, branding, Brazilian pricing and final UI. Milestone 5 — Testing & Launch Bug fixes, security review, deployment and submission to Apple App Store and Google Play. Final payment after source-code handover and successful deployment. When Applying Please answer the following: 1. Have you previously built an AI/LLM application? Please provide examples. 2. Have you integrated OpenAI or other major AI APIs? 3. Do you recommend Flutter, React Native or native development for this project? Why? 4. Have you implemented subscriptions and payment systems? 5. Do you have experience with PIX/Brazilian payment providers? 6. Can you build the web application, mobile applications, backend and admin dashboard? 7. Will we receive the COMPLETE source code? 8. Are there any recurring licensing fees associated with your proposed solution? 9. How long would you estimate the MVP will take? 10. What is your fixed-price estimate for the MVP? Budget We are looking for competitive proposals and are open to developers worldwide. Target MVP budget: GIVE US QUOTE depending on experience, existing technology/source code, features and delivery timeline. Please do not submit a generic proposal. Start your application with the words: “BRAZIL AI” Then briefly explain how you would approach this project and provide examples of similar AI applications you have built.