📄 PDF Hub

A Complete PDF Processing Toolkit for Android

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📑 Table of Contents

• Project Overview
• Problem Statement
• Solution
• Tech Stack
• Architecture
• Performance Optimizations
• Screenshots
• Getting Started
• Play Store
• Disclaimer
• Author
• License

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📋 Project Overview

PDF Hub is a feature-rich, offline-capable PDF processing application built with Flutter. It provides professional-grade PDF tools including OCR text extraction, document compression, merging, splitting, annotation, and format conversion — all within a beautiful, responsive UI.

✨ Key Features

Feature	Description
📝 OCR Text Extraction	Extract text from scanned PDFs using Google ML Kit
🗜️ Smart Compression	Reduce PDF file sizes while maintaining quality
🔗 Merge PDFs	Combine multiple PDF documents into one
✂️ Split PDFs	Extract specific pages from documents
🎨 Annotate	Add highlights, drawings, text notes, and shapes
🔄 Rotate Pages	Rotate individual or all pages
🖼️ Image to PDF	Convert images to PDF documents
💧 Watermark	Add text or image watermarks
🔢 Page Numbers	Add customizable page numbering
📊 Convert Formats	PDF to Image, Word, Excel, PowerPoint

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🎯 Problem Statement

Mobile users often need to process PDF documents on-the-go but face limitations:

• Most PDF apps require internet connectivity
• Free apps are cluttered with intrusive ads
• Premium features are locked behind expensive subscriptions
• Many apps have poor UI/UX on mobile devices

💡 Solution

PDF Hub addresses these challenges by providing:

• Offline-first architecture — All core features work without internet
• Clean, intuitive UI — Material Design 3 with dark/light mode support
• Comprehensive toolset — 10+ PDF tools in one app
• Performance optimized — Memory-efficient processing for mobile devices
• Ad-supported free tier — Full functionality with unobtrusive ads

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🛠️ Tech Stack

Category	Technologies
Framework	Flutter 3.27, Dart 3.5
State Management	Provider
PDF Processing	Syncfusion PDF, pdf, printing
OCR Engine	Google ML Kit Text Recognition
Ads	Google Mobile Ads
In-App Purchases	in_app_purchase
File Handling	file_picker, share_plus, path_provider
UI Components	flutter_svg, lottie, shimmer

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🏗️ Architecture

The project follows a feature-first architecture with clear separation of concerns:

lib/
├── core/               # Core utilities and constants
├── features/           # Feature modules (OCR, compress, merge, etc.)
│   ├── annotate/
│   ├── compress/
│   ├── convert/
│   ├── home/
│   ├── merge/
│   ├── ocr/
│   ├── rotate/
│   ├── split/
│   ├── watermark/
│   └── ...
├── models/             # Data models
├── screens/            # Shared screens (splash, settings, etc.)
├── services/           # Business logic and external integrations
│   ├── ad_service.dart
│   ├── pdf_ocr_service.dart
│   ├── pdf_merger_service.dart
│   └── ...
├── utils/              # Helper utilities
├── widgets/            # Reusable UI components
└── main.dart           # Application entry point

Key Engineering Decisions

1. Feature-First Structure: Each feature is self-contained with its own screens, making the codebase scalable and maintainable.

2. Service Layer Pattern: All business logic is abstracted into services, enabling easy testing and modification.

3. Memory-Optimized OCR: Implemented page limits (max 5 pages), reduced DPI (120), and disabled image enhancement to prevent crashes on low-end devices.

4. Graceful Degradation: Non-Latin OCR scripts fallback to Latin if models fail to load.

5. Responsive Design: Uses MediaQuery and custom ResponsiveUtils for adaptive layouts across screen sizes.

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⚡ Performance Optimizations

Optimization	Implementation
Memory Management	Limited OCR to 5 pages max, reduced rendering DPI
Crash Prevention	Try-catch wrappers around ML Kit operations
Ad Loading	Preloaded banner and interstitial ads for faster display
Theme Performance	Cached theme calculations, avoided rebuilds
Lazy Loading	History and file lists use lazy loading

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📱 Screenshots

Home	Convert	Merge	OCR

Compress	Watermark	Image to PDF	Rotate

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🚀 Getting Started

Prerequisites

• Flutter SDK 3.27+
• Android Studio / VS Code
• Android SDK 21+

Installation

# Clone the repository
git clone https://github.com/Nishanth619/PDF-Hub.git

# Navigate to project directory
cd PDF-Hub

# Install dependencies
flutter pub get

# Run the app
flutter run

Environment Setup

Create a .env file in the root directory:

BANNER_AD_ID=your_banner_ad_id
INTERSTITIAL_AD_ID=your_interstitial_ad_id

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📦 Play Store

Status: Currently in Closed Testing

The app will be available on Google Play Store soon.

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⚠️ Disclaimer

This is a personal project created for educational and portfolio purposes. Some features use third-party libraries and services:

• PDF processing powered by Syncfusion Flutter PDF
• OCR powered by Google ML Kit
• UI icons from Material Design

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👤 Author

Nishanth Ardhya

• GitHub: @Nishanth619

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📄 License

This project is proprietary software. All rights reserved.

© 2026 Nishanth Ardhya. Unauthorized copying, modification, or distribution is prohibited.

See LICENSE for more details.