C# Course - Interactive Learning App

About

C# Course is an advanced pre-launch mobile learning platform for learning C# through structured lessons, interactive quizzes, practical coding exercises, progress tracking and gamification.The product is built with Flutter and Firebase and is currently focused on Android. It is designed as a real subscription-based educational product rather than a simple course template or UI prototype.WHAT IS ALREADY BUILTLearning experience• Structured C# course content with progressive learning paths• Lessons organized into sections, topics and stages• Interactive multiple-choice quizzes• Practical coding exercises and code-based challenges• Explanations and learning feedback• Course progress tracking• Lesson completion logic• Progress indicators and completion states• Practice/test section• Learning streak system• Daily progress and gamification features• Unlockable/progression-oriented learning experienceUser experience• User registration and authentication• Google Sign-In support• User profiles• Persistent learning progress• English localization• Polish localization• Ukrainian localization• Russian localization• In-app language switching• Light and dark themes• Responsive Flutter UI• Accessibility/reduced visual effects support• Account and privacy-related flowsPremium & subscription system• Direct Google Play Billing integration• Subscription product and multiple base plans• Monthly, three-month and annual subscription architecture• Server-side purchase verification• Backend-owned purchase acknowledgement• Subscription restoration• Subscription plan changes• User-to-purchase ownership protection• Duplicate purchase protection• Premium entitlement management• Server-authoritative premium access• Google Play Real-Time Developer Notifications integration• Automatic entitlement reconciliation through the Google Play Developer APIBackend & infrastructure• Firebase Authentication• Cloud Firestore• Firebase Functions backend• Firebase App Check protection• Google Play Developer API integration• Pub/Sub integration for Google Play RTDN• Backend entitlement reconciliation• Secure token handling• Purchase-token hashing instead of storing raw purchase tokens• Production-oriented security checks and validation• Automated backend tests• Automated Flutter tests• Release validation tooling• Google Play / Data Safety preparation documentationARCHITECTUREAndroid app→ Google Play Billing→ Firebase Functions→ Google Play Developer API→ Firestore premium entitlementGoogle Play subscription events→ Real-Time Developer Notifications→ Pub/Sub→ Firebase Functions→ Google Play Developer API→ entitlement reconciliationGoogle Play and the backend are authoritative for subscription status, reducing reliance on client-side purchase state and providing a much stronger foundation for a production subscription app.TECH STACK• Flutter / Dart• Firebase Authentication• Cloud Firestore• Firebase FunctionsC# Course is an advanced pre-launch mobile learning platform for learning C# through structured lessons, interactive quizzes, practical coding exercises, progress tracking and gamification.The product is built with Flutter and Firebase and is currently focused on Android. It is designed as a real subscription-based educational product rather than a simple course template or UI prototype.WHAT IS ALREADY BUILTLearning experience• Structured C# course content with progressive learning paths• Lessons organized into sections, topics and stages• Interactive multiple-choice quizzes• Practical coding exercises and code-based challenges• Explanations and learning feedback• Course progress tracking• Lesson completion logic• Progress indicators and completion states• Practice/test section• Learning streak system• Daily progress and gamification features• Unlockable/progression-oriented learning experienceUser experience• User registration and authentication• Google Sign-In support• User profiles• Persistent learning progress• English localization• Polish localization• Ukrainian localization• Russian localization• In-app language switching• Light and dark themes• Responsive Flutter UI• Accessibility/reduced visual effects support• Account and privacy-related flowsPremium & subscription system• Direct Google Play Billing integration• Subscription product and multiple base plans• Monthly, three-month and annual subscription architecture• Server-side purchase verification• Backend-owned purchase acknowledgement• Subscription restoration• Subscription plan changes• User-to-purchase ownership protection• Duplicate purchase protection• Premium entitlement management• Server-authoritative premium access• Google Play Real-Time Developer Notifications integration• Automatic entitlement reconciliation through the Google Play Developer APIBackend & infrastructure• Firebase Authentication• Cloud Firestore• Firebase Functions backend• Firebase App Check protection• Google Play Developer API integration• Pub/Sub integration for Google Play RTDN• Backend entitlement reconciliation• Secure token handling• Purchase-token hashing instead of storing raw purchase tokens• Production-oriented security checks and validation• Automated backend tests• Automated Flutter tests• Release validation tooling• Google Play / Data Safety preparation documentationARCHITECTUREAndroid app→ Google Play Billing→ Firebase Functions→ Google Play Developer API→ Firestore premium entitlementGoogle Play subscription events→ Real-Time Developer Notifications→ Pub/Sub→ Firebase Functions→ Google Play Developer API→ entitlement reconciliationGoogle Play and the backend are authoritative for subscription status, reducing reliance on client-side purchase state and providing a much stronger foundation for a production subscription app.TECH STACK• Flutter / Dart• Firebase Authentication• Cloud Firestore• Firebase Functions• Firebase App Check• Google Play Billing• Google Play Developer API• Google Cloud Pub/Sub• Automated Flutter and backend testingWHAT THE BUYER GETSThe sale can include:• Complete Flutter application source code• Backend source code• Subscription infrastructure• Course and learning system• Quiz and coding-practice system• Localization architecture• Progress and gamification systems• Automated tests• Technical documentation• Release/security validation tooling• Existing project structure needed to continue development and prepare the product for launchCURRENT STATUSThe application is pre-launch and has not yet been publicly released on Google Play.It currently has no established user base or verified revenue.The core product, learning system, backend and subscription architecture are already implemented. The project is currently in final QA and UI-polish stages before a potential production release.This makes it suitable for a buyer who wants to avoid building an educational mobile platform from scratch and instead acquire an advanced codebase that can be rebranded, expanded with additional course content, localized further, or developed into a broader programming-learning business.This is not a basic Flutter template. It is a substantial mobile learning product with authentication, structured educational content, interactive learning, progress systems, gamification, localization, subscription infrastructure, server-side Google Play verification and production-oriented backend security already implemented.