Subscription & Entitlement Engine

A backend-first Subscription & Entitlement Management System built with Django and Django REST Framework. This application manages plans, subscriptions, usage limits, and meters in a clean, scalable, and industry-aligned way.

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🚀 Features

• 🔐 JWT Authentication (Login / Secure APIs)
• 📦 Subscription Plans (Free, Basic, Pro, etc.)
• 📊 Usage Meters (API calls, credits, feature usage)
• 🚦 Entitlements & Limits per plan
• 🔁 Atomic Transactions (ACID compliant)
• 🧩 Modular App Design (Subscriptions, Metering, Core)
• 📈 Scalable & Production-Ready Architecture

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🏗️ Tech Stack

• Backend: Django 5.x, Django REST Framework
• Auth: JWT (djangorestframework-simplejwt)
• Database: PostgreSQL (SQLite for local dev)
• Caching (optional): Redis
• API Docs: DRF / Swagger (optional)

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📁 Project Structure

subscriptionEngine/
│── core/              # Users, base models, utilities
│── subscriptions/     # Plans, subscriptions, entitlements
│── metering/          # Usage meters & limits
│── resources/         # Courts, coaches, equipment (if enabled)
│── manage.py
│── requirements.txt

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🔐 Authentication Flow

1. User logs in using /api/token/
2. Receives access & refresh tokens
3. Access token is sent in headers:

Authorization: Bearer <access_token>

4. Protected APIs validate subscription & limits

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📦 Subscription Flow (High Level)

1. User subscribes to a plan

2. Plan defines:

   • Feature access
   • Usage limits

3. Each API call:

   • Checks active subscription
   • Validates entitlement
   • Updates usage meter atomically

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🧠 Key Concepts Used

• ACID Transactions (transaction.atomic())
• Row-level locking to prevent race conditions
• Clean separation of concerns
• RESTful API design

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⚙️ Setup Instructions

1️⃣ Clone Repository

git clone <repo-url>
cd subscriptionEngine

2️⃣ Create Virtual Environment

python -m venv venv
source venv/bin/activate   # Windows: venv\\Scripts\\activate

3️⃣ Install Dependencies

pip install -r requirements.txt

4️⃣ Configure Database

Update settings.py:

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': 'subscription_db',
        'USER': 'postgres',
        'PASSWORD': 'password',
        'HOST': 'localhost',
        'PORT': '5432',
    }
}

5️⃣ Migrate & Run

python manage.py makemigrations
python manage.py migrate
python manage.py runserver

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🧪 API Example

Get active subscription details

GET /api/subscriptions/me/

Response:

{
  "plan": "Pro",
  "limits": {
    "api_calls": 1000
  },
  "usage": {
    "api_calls": 120
  }
}

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🔮 Future Enhancements

• Payment gateway integration (Stripe / Razorpay)
• Webhook-based subscription updates
• Admin analytics dashboard
• Rate limiting middleware
• Flutter / React frontend integration

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👤 Author

Aryan Singh Backend Developer | Django | REST APIs

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