LinguaAI | Flutter App | Education

LinguaAI — Speak Any Language with AI

LinguaAI is a complete, production-ready AI language learning app built with Flutter. It combines the power of OpenAI GPT-4o and Google Gemini to deliver an immersive, personalized learning experience across 20 languages.

Whether you’re building a language learning startup or adding AI-powered education to your portfolio, LinguaAI gives you everything you need — ready to customize, rebrand, and publish.

Download Demo APK

Key Features

AI-Powered Learning

• AI Conversation — 5 modes: Free Chat, Scenario, Guided Lesson, Role Play, Correction Mode (powered by OpenAI GPT-4o)
• AI Vocabulary Cards — Generate flashcards with pronunciation, examples, and cultural notes (powered by Google Gemini)
• AI Grammar Lessons — Auto-generated lessons with concept explanation, examples, and interactive practice
• AI Stories — Generate reading stories by theme and level with tappable word translation and comprehension quizzes
• Daily Challenge — Word of the day, phrase of the day, and mini quiz

Smart Learning System

• SM-2 Spaced Repetition — Scientifically-proven algorithm for optimal vocabulary retention
• CEFR Level Assessment — A1 to C2 level placement with personalized content
• Learning Path — Visual node-based curriculum with completion tracking
• Pronunciation Guide — IPA phonemes with audio playback
• TTS & STT — Text-to-speech and speech-to-text for all 20 languages

20 Target Learning Languages

Spanish · French · Japanese · Chinese · German · Korean · Italian · Portuguese · Arabic (RTL) · Hindi · Russian · Dutch · Turkish · Swedish · Polish · Greek · Vietnamese · Thai · Indonesian · Ukrainian

Note: These are the languages learners can study. The app interface itself is in English.

Gamification

• 30 Levels with XP progression
• 25 Badges — unlockable achievements
• Streak System — daily practice tracking with fire emoji
• Hearts System — limited attempts that refresh daily
• XP Chart — weekly progress visualization
• Celebration Animations — confetti overlay on achievements

Full Monetization

• RevenueCat — 3 subscription tiers (Monthly $4.99, Yearly $29.99, Lifetime $49.99)
• Google AdMob — Banner ads on main tabs + interstitial ads after sessions
• Premium Gate — Ads hidden for premium users
• Free Tier Limits — Configurable via Firebase Remote Config (no rebuild needed)

Authentication

• Email/Password registration and login
• Google Sign-In (Android & iOS)
• Apple Sign-In (iOS only)
• Forgot password with email reset
• User-friendly error messages

User Experience

• Onboarding Flow — 4-slide intro, native language picker, target language selection, CEFR assessment
• Dark Mode — Warm dark theme (not cold black)
• RTL Support — Full Arabic right-to-left layout
• Custom Transitions — Fade, slide-up, and scale animations
• Offline SRS — Review vocabulary without internet
• Push Notifications — FCM + local streak reminders

️ Tech Stack

What You Get

• Full Flutter source code (Android + iOS)
• 15+ screens, 15+ providers, 15+ Freezed models
• 81 unit tests
• Comprehensive HTML documentation (offline)
• Quick start guide with step-by-step setup
• Firestore security rules template
• 6 months of support

⚡ Quick Setup

1. Create Firebase project, add google-services.json and GoogleService-Info.plist
2. Enable Authentication (Email, Google, Apple)
3. Add OpenAI and Gemini API keys to Firebase Remote Config
4. Run flutter pub get and flutter run

Detailed setup instructions included in the documentation.

Requirements

• Flutter SDK 3.29.2+ (Dart SDK 3.7.2+)
• Firebase account (free tier works for development)
• OpenAI API key (pay-as-you-go, ~$0.10-0.50/user/month)
• Google Gemini API key (free tier available)
• RevenueCat account (free for <$2.5k/month revenue)
• AdMob account (optional)

Screenshots

Browse the item preview gallery above for full-resolution screenshots covering: onboarding flow, AI conversation (5 modes), vocabulary SRS, AI grammar lessons, AI stories with tappable translations, daily challenge, learning path, paywall, profile, and dark mode.

Documentation

Comprehensive offline HTML documentation is included with the source download. Open Documentation/index.html in any browser for the full guide, or QuickStart/quick-start.html for a 15-minute step-by-step setup.

The documentation covers:

• Firebase project setup (Auth, Firestore, Remote Config, FCM)
• Production-ready Firestore security rules
• RevenueCat in-app purchase configuration
• AdMob banner and interstitial ad setup
• OpenAI and Gemini API key configuration with cost breakdown
• Android release signing (keystore + key.properties)
• iOS Apple Sign-In, APNs, and Info.plist permissions
• 12-point production checklist
• Troubleshooting guide (build, Firebase, AI, monetization, runtime)

⚠️ Third-Party Service Costs (Not Included)

This item’s purchase price covers the source code only. The third-party services listed below are required to run the app and are NOT included in the item price. Buyers are responsible for any usage-based or subscription fees charged directly by the providers:

• OpenAI API — pay-as-you-go. Estimated $0.10–0.50 per active user per month for typical usage. Pricing: openai.com/pricing
• Google Gemini API — generous free tier; paid pricing applies above quota. Pricing: ai.google.dev/pricing
• RevenueCat — free up to $2,500/month tracked revenue; percentage fee applies above that threshold. Pricing: revenuecat.com/pricing
• Firebase — Spark (free) tier is sufficient for development and small user bases; Blaze (pay-as-you-go) applies once free quotas are exceeded. Pricing: firebase.google.com/pricing
• Google AdMob — no cost to use; revenue share applies on impressions.
• Apple Developer Program — $99/year (required for App Store publishing).
• Google Play Developer — $25 one-time fee (required for Play Store publishing).

A detailed cost breakdown with per-request and per-user monthly estimates is provided in the included documentation.

Support

We provide dedicated support for all buyers:

• Email: devsnack26@gmail.com
• WhatsApp: +855 967 413 911

Response time: within 24 hours on business days.

Support includes:

• Help with initial setup and configuration
• Firebase and API key configuration assistance
• Bug fixes related to the original source code
• General questions about customization

Note: Support does not cover custom feature development, third-party service issues, or modified source code bugs.

Changelog

v1.0.0 — Initial Release

• 24 features across 6 development phases
• 20 target learning languages with RTL Arabic (app UI is English-only)
• AI conversation, vocabulary, grammar, stories, daily challenge
• SM-2 spaced repetition system
• Gamification with 30 levels and 25 badges
• RevenueCat subscriptions + AdMob ads
• Email, Google, and Apple authentication
• Dark mode + custom screen transitions
• 81 unit tests
• Comprehensive offline documentation