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🤖 Documind - AI Document Assistant

Documind Banner

Transform your documents into intelligent conversations

React FastAPI Python LangChain ChromaDB

Features • Demo • Installation • Usage • Architecture • Deployment

📋 Table of Contents

🌟 Overview

Documind is an intelligent AI-powered document assistant that enables you to have natural conversations with your documents. Upload PDFs, ask questions, and get accurate answers backed by source citations using advanced Retrieval-Augmented Generation (RAG) technology.

Why Documind?

  • 🎯 Accurate Answers: Get precise information from your documents with source citations
  • 💬 Natural Conversations: Chat with your documents as if talking to an expert
  • 🔒 Secure & Private: User-specific document storage with JWT authentication
  • 📚 Multiple Documents: Manage and chat with multiple documents independently
  • 🚀 Fast & Efficient: Built with modern async frameworks for optimal performance
  • 💾 Persistent History: All conversations are saved and retrievable

✨ Features

🔐 Authentication & Security

  • User Registration & Login with JWT token-based authentication
  • Password Hashing using bcrypt for secure credential storage
  • Protected Routes ensuring only authenticated users access resources
  • User Isolation - each user can only access their own documents

📄 Document Management

  • PDF Upload with drag-and-drop interface
  • Automatic Processing - documents are chunked and embedded automatically
  • Document-Specific Chats - each document has its own conversation thread
  • Delete Documents - easy document management
  • Multi-Document Support - upload and manage multiple documents

💬 Intelligent Chat

  • RAG-Powered Responses using vector similarity search
  • Context-Aware Answers based on document content
  • Source Citations with exact page references
  • Chat History persisted per document per user
  • Real-Time Streaming for responsive user experience

🎨 Modern UI/UX

  • ChatGPT-Inspired Interface for familiar user experience
  • Responsive Design works on desktop and mobile
  • Dark Mode Ready (optional feature)
  • Interactive Sidebar for document navigation
  • Markdown Support for formatted responses

🛠️ Tech Stack

Backend

  • FastAPI - Modern, fast web framework for building APIs
  • LangChain - Framework for developing LLM applications
  • ChromaDB - Vector database for embeddings
  • OpenAI API - (via OpenRouter) for LLM completions
  • Sentence Transformers - Free local embeddings
  • SQLite - Lightweight database for user data and chat history
  • JWT - JSON Web Tokens for secure authentication

Frontend

AI/ML

  • LangChain - Orchestration framework
  • ChromaDB - Vector store for semantic search
  • Sentence Transformers - all-MiniLM-L6-v2 for embeddings
  • OpenRouter - Access to multiple LLMs (GPT-4, Claude, etc.)

🏗️ Architecture

┌─────────────────────────────────────────────────────────────┐
│                         Frontend (React)                     │
│  ┌──────────────┐  ┌──────────────┐  ┌──────────────┐      │
│  │   Auth UI    │  │  Document    │  │  Chat UI     │      │
│  │              │  │  Management  │  │              │      │
│  └──────────────┘  └──────────────┘  └──────────────┘      │
└─────────────────────────────────────────────────────────────┘
                            │ HTTP/REST
┌─────────────────────────────────────────────────────────────┐
│                      Backend (FastAPI)                       │
│  ┌──────────────┐  ┌──────────────┐  ┌──────────────┐      │
│  │ Auth Routes  │  │  API Routes  │  │ RAG Service  │      │
│  │   (JWT)      │  │              │  │              │      │
│  └──────────────┘  └──────────────┘  └──────────────┘      │
│                            │                                 │
│  ┌──────────────┐  ┌──────────────┐  ┌──────────────┐      │
│  │   SQLite     │  │   ChromaDB   │  │  LLM Client  │      │
│  │  (Users,     │  │  (Vectors)   │  │ (OpenRouter) │      │
│  │   History)   │  │              │  │              │      │
│  └──────────────┘  └──────────────┘  └──────────────┘      │
└─────────────────────────────────────────────────────────────┘

Data Flow

  1. User uploads PDF → Processed into chunks → Embedded with Sentence Transformers → Stored in ChromaDB
  2. User asks question → Embedded with same model → Similar chunks retrieved from ChromaDB
  3. Retrieved context + Question → Sent to LLM via OpenRouter → Response streamed back
  4. Chat history → Saved to SQLite → Loaded when document is selected

🚀 Installation

Prerequisites

  • Python 3.11+
  • Node.js 16+ and npm
  • Git

1. Clone the Repository

git clone https://github.com/saadkhan2003/Documind---AI-Document-Assistant.git
cd Documind---AI-Document-Assistant

2. Backend Setup

# Install Python dependencies
pip install -r requirements.txt

# Create .env file
# Copy the example below and add your API keys

Create a .env file in the root directory:

# OpenRouter API Key (get from https://openrouter.ai/)
OPENROUTER_API_KEY=your_openrouter_api_key_here

# JWT Secret (generate a random string)
JWT_SECRET_KEY=your_secret_key_here_use_openssl_rand_hex_32

# Optional: Change default model
LLM_MODEL=openai/gpt-3.5-turbo

3. Frontend Setup

cd frontend
npm install

4. Database Initialization

The SQLite database will be created automatically on first run. The schema includes:

  • users - User accounts
  • user_documents - Document metadata and ownership
  • chat_history - Conversation history per document

⚙️ Configuration

Backend Configuration

Edit src/utils/config.py to customize:

# Embedding Model (free, runs locally)
EMBEDDING_MODEL = "all-MiniLM-L6-v2"

# LLM Model (via OpenRouter)
LLM_MODEL = os.getenv("LLM_MODEL", "openai/gpt-3.5-turbo")

# Chunk Settings
CHUNK_SIZE = 1000
CHUNK_OVERLAP = 200

# Vector Store
CHROMA_PERSIST_DIR = "./vectorstore"

Frontend Configuration

Edit src/index.js or create .env in frontend folder:

REACT_APP_API_URL=http://localhost:8000

💻 Usage

Starting the Application

Terminal 1 - Backend:

# From project root
python -m uvicorn src.api.main:app --reload --host 0.0.0.0 --port 8000

Terminal 2 - Frontend:

# From frontend folder
cd frontend
npm start

The application will open at http://localhost:3000

Using Documind

  1. Register/Login

    • Open the application
    • Create a new account or login
    • You'll be redirected to the main interface

  2. Upload Documents

    • Drag and drop a PDF file or click to browse
    • Wait for processing (automatic chunking and embedding)
    • Document appears in the sidebar

  3. Start Chatting

    • Click on a document to select it
    • Type your question in the chat input
    • Get AI-powered answers with source citations
    • Chat history is automatically saved

  4. Manage Documents

    • Switch between documents by clicking them
    • Delete documents you no longer need
    • Each document maintains its own chat history

📚 API Documentation

Authentication Endpoints

POST /auth/register
POST /auth/login
POST /auth/token

Document Endpoints

POST /upload          # Upload PDF document
GET  /documents       # Get user's documents
DELETE /documents/{doc_id}  # Delete document

Chat Endpoints

POST /query           # Ask question about document
GET  /chat_history/{doc_id}  # Get chat history

Interactive API Docs

Visit http://localhost:8000/docs for interactive Swagger documentation.

🌐 Deployment

Deploy on Render

  1. Backend Deployment

    • Connect your GitHub repository
    • Use render.yaml configuration
    • Add environment variables (OPENROUTER_API_KEY, JWT_SECRET_KEY)
    • Deploy!

  2. Frontend Deployment

    • Deploy to Netlify or Vercel
    • Use netlify.toml configuration
    • Set REACT_APP_API_URL to your backend URL
    • Build and deploy!

Deploy on Railway

# Install Railway CLI
npm install -g @railway/cli

# Login and deploy
railway login
railway init
railway up

Environment Variables for Production

# Backend
OPENROUTER_API_KEY=your_production_key
JWT_SECRET_KEY=strong_random_secret
DATABASE_URL=your_production_db_url (optional)
CORS_ORIGINS=https://your-frontend-url.com

# Frontend
REACT_APP_API_URL=https://your-backend-url.com

📖 Project Structure

.
├── src/
│   ├── api/              # API routes and endpoints
│   │   ├── main.py       # Main FastAPI application
│   │   └── auth_routes.py # Authentication endpoints
│   ├── core/             # Core functionality
│   │   ├── embeddings.py # Embedding generation
│   │   ├── llm_client.py # LLM interaction
│   │   └── vectorstore.py # Vector database operations
│   ├── models/           # Data models
│   │   └── database.py   # SQLite models and operations
│   ├── processors/       # Document processors
│   │   └── pdf_processor.py # PDF parsing and chunking
│   ├── services/         # Business logic
│   │   └── rag_service.py # RAG implementation
│   └── utils/            # Utilities
│       ├── auth.py       # JWT and authentication
│       ├── chunking.py   # Text chunking strategies
│       └── config.py     # Configuration management
├── frontend/
│   ├── public/           # Static assets
│   └── src/
│       ├── App.js        # Main React component
│       ├── Auth.js       # Authentication components
│       ├── AuthContext.js # Auth state management
│       └── index.js      # Entry point
├── data/                 # Uploaded documents
├── vectorstore/          # ChromaDB persistence
├── requirements.txt      # Python dependencies
├── netlify.toml         # Netlify configuration
├── render.yaml          # Render configuration
└── README.md            # This file

🤝 Contributing

Contributions are welcome! Please follow these steps:

  1. Fork the repository
  2. Create a feature branch (git checkout -b feature/AmazingFeature)
  3. Commit your changes (git commit -m 'Add some AmazingFeature')
  4. Push to the branch (git push origin feature/AmazingFeature)
  5. Open a Pull Request

Development Guidelines

  • Follow PEP 8 for Python code
  • Use ESLint/Prettier for JavaScript code
  • Write meaningful commit messages
  • Add tests for new features
  • Update documentation as needed

🐛 Troubleshooting

Common Issues

Backend won't start:

# Check if port 8000 is already in use
netstat -ano | findstr :8000
# Kill the process or use a different port

Frontend can't connect to backend:

  • Verify backend is running on http://localhost:8000
  • Check CORS settings in main.py
  • Ensure .env has correct REACT_APP_API_URL

Embedding generation is slow:

  • First run downloads the model (~80MB)
  • Subsequent runs are much faster
  • Consider using GPU acceleration if available

OpenRouter API errors:

  • Verify your API key is correct
  • Check your OpenRouter account has credits
  • Try a different model if one is unavailable

📝 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

📧 Contact

Saad Khan - @saadkhan2003

Project Link: https://github.com/saadkhan2003/Documind---AI-Document-Assistant

⭐ Star this repo if you find it helpful!

Made with ❤️ using React, FastAPI, and LangChain

About

Documind is an intelligent AI document assistant that enables natural conversations with your PDF documents. Powered by advanced RAG (Retrieval-Augmented Generation) technology, it combines React, FastAPI, LangChain, and ChromaDB to deliver accurate answers with source citations. Click on the link for live demo.

documind-ai-document-assistant.vercel.app

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