PostAI - AI Social Media Caption Generator & Content Creator Flutter App (Android & iOS)

PostAI — AI-Powered Social Media Content Creator

PostAI is a complete Flutter mobile app that uses AI (OpenAI GPT-4o & Google Gemini) to generate social media captions, viral hooks, hashtag research, content repurposing, A/B testing, brand voice training, and content calendar management — all optimized per platform.

Built with clean architecture, Riverpod state management, Firebase backend, and ready-to-publish monetization (RevenueCat + AdMob). Just add your API keys and launch.

Download Demo APK

Key Features

• AI Caption Generator — Generate platform-optimized captions for Instagram, TikTok, LinkedIn, and Twitter/X. Choose tone, content type, and niche. Multiple captions per generation.
• Viral Hook Writer — 5 scroll-stopping opening hooks per topic across 6 styles: Curiosity, Controversy, Value, Story, Question, Bold Claim.
• Hashtag Research — Tiered hashtag packs (Mega 10M+, Mid 500K–10M, Niche under 500K) with real tag recommendations per platform.
• Content Repurpose Engine — Paste one piece of content and instantly adapt it to feel 100% native on every platform.
• Brand Voice Training — Train the AI on your writing style from examples. Apply your unique brand voice to all future generations.
• A/B Caption Tester — Objectively score and compare two captions with detailed breakdowns on hook strength, clarity, CTA, platform fit, and engagement potential.
• Content Calendar — Plan and schedule posts with AI-generated content ideas. Monthly grid view with status tracking (draft, scheduled, posted).
• Caption Library — Save, favorite, search, and filter all your generated captions by platform.

Supported Platforms

• Instagram — Long-form captions, 25 hashtags, emoji-rich
• ▶️ TikTok — Short punchy captions, trending hooks
• LinkedIn — Professional storytelling, thought leadership
• Twitter / X — Under 280 chars, bold and opinionated

Dual AI Support

• OpenAI GPT-4o / GPT-4o-mini — Primary AI provider for high-quality generation
• Google Gemini — Secondary provider, switchable via Firebase Remote Config
• Hot-swap between providers without app update

Built-in Monetization

• RevenueCat — Subscription management (monthly/yearly) with premium entitlements
• AdMob — Banner and interstitial ads for free tier users
• Free Tier Limits — Configurable daily limits via Remote Config (5 captions, 3 hooks, 2 hashtags, 2 repurpose, 1 A/B test per day)
• Paywall Screen — Beautiful paywall with feature comparison

Authentication

• Email / Password registration & login
• Google Sign-In
• Apple Sign-In
• Forgot Password flow

Beautiful UI

• Warm coral-to-orange gradient brand identity
• Poppins typography throughout
• Full Dark Mode support with system preference detection
• Smooth animations (Lottie + Flutter Animate)
• Shimmer loading states on every async operation
• Illustrated empty states on all list screens
• Platform-colored badges, chips, and character counters

️ Tech Stack

• Flutter 3.24+ — Android & iOS from a single codebase
• Dart 3.5+ — Full sound null safety
• Riverpod 2.x — Reactive state management
• GoRouter — Declarative navigation with auth guards
• Firebase — Auth, Cloud Firestore, Remote Config, Cloud Messaging
• Dio — HTTP client for AI API calls
• Freezed — Immutable data models with JSON serialization
• Hive + SharedPreferences — Local storage
• Material 3 — Modern design system with custom theme extensions

What You Get

• Full Flutter source code (Android + iOS)
• Clean architecture with separation of concerns
• Offline HTML documentation with setup guide
• Firebase security rules included
• Step-by-step setup guide
• All AI prompt templates — fully customizable
• Ready for App Store and Play Store submission

⚡ Quick Setup

1. Create Firebase project (Auth + Firestore + Remote Config + FCM)
2. Add google-services.json and GoogleService-Info.plist
3. Set your OpenAI API key in Firebase Remote Config
4. Run flutter pub get and dart run build_runner build
5. Run the app — done!

Requirements

• Flutter SDK 3.24 or later
• Android Studio or VS Code
• Firebase project (Blaze plan recommended)
• OpenAI API key (GPT-4o access)
• Google Gemini API key (optional)
• RevenueCat account (for subscriptions)
• AdMob account (for ads)

Changelog

Version 1.0.0 — April 2026 (Initial Release)

• [NEW] AI caption generator with multi-platform support (Instagram, TikTok, LinkedIn, Twitter/X)
• [NEW] Viral hook writer with 6 hook styles
• [NEW] Tiered hashtag research (mega, mid, niche)
• [NEW] Cross-platform content repurpose engine
• [NEW] Brand voice training from writing samples
• [NEW] A/B caption testing with objective scoring
• [NEW] Content calendar with AI-generated ideas
• [NEW] Caption library with favorites, search, and platform filter
• [NEW] Firebase Auth (Email, Google, Apple Sign-In)
• [NEW] RevenueCat subscription integration
• [NEW] AdMob banner and interstitial ads
• [NEW] Full dark mode support
• [NEW] Push notifications via FCM + local reminders
• [NEW] Dual AI support: OpenAI GPT-4o + Google Gemini

Support

We’re here to help you get up and running. Reach out anytime:

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

We typically respond within 24 hours. When reporting issues, please include your Flutter version and any error messages or screenshots.

PostAI — Create. Post. Grow.