API Rate Limiter System (with API Key, Daily Limits & Email Notifications)

This project implements a robust API Rate Limiting System that restricts API usage based on user subscription plans (basic, pro, premium). It features API key generation, daily usage tracking, email alerts at 90% and 100% usage, and CSV reporting via cron job.

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📌 Key Features

• 🔐 API Key Generation for each user.
• 📊 Daily API Usage Tracking per user via MongoDB.
• ⚠️ Automatic Email Warning at 90% usage.
• ⛔ Limit Reached Email and block at 100% usage.
• 📬 Daily CSV Usage Report emailed to admin at 8 AM.
• 🔁 Usage Reset every midnight via scheduled cron.
• 🔁 API Key Regeneration (admin only).
• 🧾 User Dashboard (Admin Route) with daily usage summary.

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🧰 Tech Stack

Layer	Tech/Tool
Backend	Node.js, Express.js
Database	MongoDB (Mongoose ODM)
Email	Nodemailer + Gmail SMTP
Scheduler	node-cron
Data Format	json2csv (CSV generation)
Security	Hashed API Keys (SHA-256)

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🧪 API Routes and Usage (Postman Guide)

1. Create User (with API Key)

POST /api/users

{
  "name": "Faizan",
  "email": "faizan@example.com",
  "plan": "basic"
}

2. Regenerate API Key (Admin)

PUT /api/admin/users/:id/apikey
Response will contain a new raw API key (shown once only).

3. Rate-Limited Test API Route

GET /api/data
Header:

x-api-key: YOUR_API_KEY_HERE

4. Admin Dashboard

GET /api/admin/dashboard
📊 Returns all users with today’s usage.

5. Update User Details

PUT /api/users/:id

{
  "name": "Updated Name",
  "email": "newemail@example.com"
}

scripts/dailyReport.js
Runs every day at 8 AM (via separate cron or manually) to:
📤 Generate CSV of daily usage
📧 Email it to ADMIN_EMAIL defined in .env

.env Configuration

Create a .env file:

PORT=3000
MONGO_URI=mongodb+srv://your-db-uri
EMAIL_USER=youremail@gmail.com
EMAIL_PASS=yourapppassword
ADMIN_EMAIL=admin@example.com

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Future Implementations

• 🔒 JWT-based authentication + role-based access.

• 💰 Stripe integration for upgrading plans.

• 📈 Analytics dashboard with charts (React/Next.js).

• 📬 Admin alerts for users hitting limits.

• 🧪 API testing dashboard (Postman clone UI).

• 📁 Download logs & reports from dashboard.

Scripts

npm run dev – Start dev server (with nodemon)

node index.js – Run usage reset cron

node scripts/dailyReport.js – Send daily CSV