LingoMeld – AI Language Conversation Tutor

LingoMeld – AI Language Conversation Tutor

A complete, production-ready language learning platform comparable in scope to Duolingo or Speak — but focused on real conversation practice powered by AI. Ships with a Flutter mobile app (iOS, Android & Web), a NestJS backend API, and a Laravel + Filament admin panel with a content CMS and web installer. Buy once, brand it, and start collecting subscribers.

✨ Key Features

💬 AI Conversation Tutor

• Free-form chat with an AI language partner powered by GPT-4o-mini via OpenRouter

• Real-time conversations via Socket.IO WebSocket gateway

• Model-agnostic — swap OpenRouter for OpenAI, Anthropic, or a self-hosted model in one place

• Full conversation history per user

🎭 Scenario-Based Practice

• Roleplay real-world situations: ordering coffee, job interview, doctor visit, travel, and more

• Scenarios managed via the Filament admin CMS — add new ones without code changes

📚 Structured Lessons

• Curriculum-based lessons grouped by language and difficulty level

• Content managed entirely from the admin panel — no deployments needed to add content

🎙️ Pronunciation Coach

• Speech analysis and feedback module built into the mobile app

🔤 Vocabulary Builder

• Spaced-repetition (SRS) word lists tied to lessons and conversations

• Word of the Day, mastered/learning/review-due tracking

• Full-text search across vocabulary

🔥 Streaks, Gamification & Daily Challenges

• XP, levels, badges, leaderboards, and confetti celebrations

• Daily challenges — bite-sized tasks to drive retention

• Streak tracking with calendar heatmap visualization

📊 Progress Tracking

• Charts (FL Chart) showing progress over time

• Activity calendar heatmap (table_calendar)

• Daily goal tracking with minute-based progress bars

🔐 Auth, Notifications & Payments

• Email/password with OTP, Google Sign-In, Apple Sign-In

• JWT access + refresh tokens with automatic rotation

• Firebase Cloud Messaging push notifications + local reminders

• In-App Purchases via StoreKit (Apple) and Play Billing (Google) with server-side receipt verification

• Stripe for web payments

• Freemium model — free tier + premium subscription

🛠️ Admin Panel (Laravel + Filament)

• Filament 3 dashboard with CRUD for every entity

• Content management for languages, lessons, scenarios, vocabulary, and challenges

• User management with role-based permissions (Spatie)

• Subscription and payment views

• Web installer wizard for non-technical buyers

• Firebase admin integration for push notification management

• At-a-glance KPI widgets

⚙️ Tech Stack

• Mobile: Flutter 3.2+ (iOS, Android & Web) — Riverpod, GoRouter, Dio, FL Chart, Socket.IO client, in_app_purchase, Lottie

• Backend: NestJS 11 + TypeScript — PostgreSQL, Redis, BullMQ, Socket.IO, Swagger (20+ modules)

• Admin: PHP 8.2, Laravel 11, Filament 3, Sanctum, Socialite, Spatie Permissions, Kreait Firebase

• AI: OpenRouter (GPT-4o-mini by default, fully swappable) + OpenAI SDK

• Auth: JWT + Refresh Tokens, Google OAuth, Apple Sign-In (JWKS), OTP via AWS SES

• Payments: Apple StoreKit, Google Play Billing, Stripe — server-side receipt verification

• Storage: Cloudflare R2 (S3-compatible) with presigned URLs

• Infra: PM2 + Nginx, Firebase FCM, scheduled jobs via @nestjs/schedule

📦 What's Included

• Flutter Mobile App — iOS, Android & Web, full source code with localization scaffolding

• NestJS Backend API — 20+ modules, SQL migrations + seed data, Swagger docs at /api/docs

• Laravel + Filament Admin — full CMS, web installer wizard, role-based permissions

• Environment files — .env.example with every variable documented

• Full README and inline documentation

💎 Subscription Plans (In-App)

• Free: Basic lessons, limited AI conversations per day, community access

• Premium: Unlimited AI conversations, all scenarios, full vocabulary SRS, advanced analytics, offline-friendly storage, priority support

• Apple App Store and Google Play receipt verification with full webhook lifecycle handling

• Stripe integration for web payments

📋 Requirements

• Flutter SDK 3.2+ with Dart 3

• Node.js 20+ and npm

• PHP 8.2+ and Composer (for Laravel admin)

• PostgreSQL 14+ database

• Redis 6+ instance

• Firebase project (Cloud Messaging / FCM)

• OpenRouter or OpenAI API key (AI tutor)

• Cloudflare R2 or S3-compatible storage bucket

• AWS SES or SMTP provider (transactional email)

• Stripe account (web payments)

• Apple Developer and/or Google Play account for IAP