BACKEND_GUIDE.md

LibraDigit AI - Understanding the Backend

✅ Your Backend IS Working!

The "Not Found" message you see when visiting http://localhost:5000 is completely normal and not an error.

🔍 Why You See "Not Found"

The Flask backend is an API server, not a website. It doesn't have web pages to display - it only responds to API requests from the frontend.

What This Means:

• ❌ http://localhost:5000 → Shows "Not Found" (this is normal!)
• ✅ http://localhost:5000/api/health → Returns JSON data
• ✅ http://localhost:5000/api/projects → Returns project list
• ✅ http://localhost:3000 → Your actual application (frontend)

🎯 How to Access the Application

The Correct URL:

http://localhost:3000 ← This is your application!

Backend URLs (API only):

These return JSON data, not web pages:

• http://localhost:5000/ → API info
• http://localhost:5000/api/health → Health check
• http://localhost:5000/api/projects → Project list

🧪 Testing the Backend

Method 1: Visit API Endpoints

Open these URLs in your browser:

1. http://localhost:5000/

   • Should show: {"name": "LibraDigit AI Backend API", ...}

2. http://localhost:5000/api/health

   • Should show: {"status": "healthy", "database": true, ...}

3. http://localhost:5000/api/projects

   • Should show: {"projects": [...]}

Method 2: Run Test Script

cd backend
python test_api.py

This will test all API endpoints automatically.

Method 3: Use the Frontend

The frontend at http://localhost:3000 automatically calls the backend API.

📊 How It Works

┌─────────────────────────────────────────────────────┐
│  Browser: http://localhost:3000                     │
│  ↓                                                   │
│  Frontend (React)                                   │
│  ↓                                                   │
│  Makes API calls to http://localhost:5000/api/...  │
│  ↓                                                   │
│  Backend (Flask)                                    │
│  ↓                                                   │
│  Database (SQLite)                                  │
└─────────────────────────────────────────────────────┘

✅ Verification Checklist

Check these to confirm everything is working:

1. Backend Running?

   • Look for: 🌐 Server running on http://localhost:5000
   • Terminal should show Flask server output

2. Frontend Running?

   • Look for: Local: http://localhost:3000/
   • Terminal should show Vite server output

3. Can Access Frontend?

   • Open: http://localhost:3000
   • Should see: LibraDigit AI dashboard

4. No Errors on Dashboard?

   • Should NOT see: "Unable to fetch projects"
   • Should see: Empty state or project list

🐛 Common Misunderstandings

❌ WRONG: "Backend shows 'Not Found' - it's broken!"

✅ CORRECT: Backend is an API. Visit http://localhost:3000 instead.

❌ WRONG: "I need to see a web page at localhost:5000"

✅ CORRECT: The web page is at localhost:3000. Port 5000 is API only.

❌ WRONG: "The backend isn't working"

✅ CORRECT: If you see JSON data at /api/health, it's working perfectly!

🎯 Quick Test

Run this in your browser:

http://localhost:5000/api/health

If you see something like:

{
  "status": "healthy",
  "database": true,
  "tesseract": false
}

Then your backend is working perfectly! ✅

📝 Summary

• Backend (API): http://localhost:5000 → Returns JSON data
• Frontend (App): http://localhost:3000 → Your actual application
• "Not Found" at :5000: This is normal! The backend is an API, not a website.
• Use the app at: http://localhost:3000

---

Your backend is working correctly! Use the application at http://localhost:3000 🚀