📘 Scalable Social Application – Technical Documentation

1. Application Overview

Application Name: SocialSphere

Purpose: A public, scalable social content platform where users can register, create posts, like/comment, follow other users, and consume a personalized feed. The system is designed with scalability, performance, and security in mind so it can support real-world public traffic.

Target Users:

• General public
• Content creators
• Students & developers (as a portfolio-grade project)

---

2. High-Level Architecture

Client (React.js)
      ↓ HTTP / HTTPS
API Gateway / Load Balancer
      ↓
Backend Services (Node.js + Express)
      ↓
Database (MongoDB)
      ↓
Cache & Rate Limit Store (Redis) //not in use now but use in future 

Architecture Style

• Client–Server Architecture
• RESTful APIs
• Horizontally scalable backend

---

3. Tech Stack

Frontend

• React.js (Next)
• Tailwind CSS

• Framer Motion // use no motion because of performance issue's

Backend

• Node.js
• Express.js
• JWT Authentication
• Resend (For Email verification)
• Bcrypt (password hashing)

Database & Storage

• MongoDB (primary data store)
• Redis (caching + rate limiting)//not in use
• Cloudinary (in use) / AWS S3 (image storage)

DevOps & Deployment

• Vercel (frontend)
• Render / Fly.io (backend)
• MongoDB Atlas
• Redis Cloud
• Nginx (reverse proxy) //work on it

---

4. Core Features

Authentication

• User registration
• Login with JWT
• verify useing resend
• Refresh tokens
• Protected routes

User System

• Profile creation

• Public profile pages

Post System

• Create, edit, delete posts
• Like & (comment added soon ) on posts
• Infinite scrolling feed

Performance & Security

• Rate limiting (Redis-based)
• Input validation
• Caching for feeds
• API pagination

---

5. Database Design

User Schema

• id
• username (unique)
• email (unique)
• passwordHash
• bio

• createdAt

Post Schema

• id
• authorId
• content
• images[]
• likes[]

• createdAt

Comment Schema //(under development)

• id
• postId
• authorId
• text
• createdAt

---

6. API Design

Auth Routes

• POST /api/auth/register
• POST /api/auth/login
• POST /api/auth/verify-code
• GET /api/auth/forget
• GET /api/auth/google-login

User Routes

• GET /api/users/:id
• GET /api/user
• POST /api/user/update
• POST /api/users/follow //(under development)

Post Routes

• POST /api/posts //(under development)
• GET /api/posts/feed //(under development)
• POST /api/posts/:id/like //(under development)
• POST /api/posts/:id/comment //(under development)

---

7. Rate Limiting (Scalable)

Why Rate Limiting?

• Prevent abuse & DDoS
• Protect login endpoints
• Maintain server stability

Implementation

• Redis-based global counters
• Shared across all backend instances

Limits Example

// change the req limit and time limit soon

Route	Limit
Login	15 req/min
Register	15 req/min
Posts Feed	15 req/min

---

8. Caching Strategy

Redis Usage

• Cache public feeds
• Cache user profiles
• Reduce database load

Cache Invalidation

• On new post creation
• On follow/unfollow actions

---

9. Security Measures

• Password hashing with bcrypt
• JWT-based auth
• Rate limiting
• CORS protection
• Input sanitization

---

10. Scalability Strategy

Horizontal Scaling

• Multiple backend instances
• Stateless APIs

Database Scaling

• Indexed queries
• Read replicas
• Sharding (future)

CDN

• Static assets served via CDN

---

11. Deployment Flow

1. Frontend deployed on Vercel
2. Backend deployed on Render/Fly.io
3. MongoDB Atlas connected
4. Redis Cloud enabled
5. Environment variables configured

---

12. Monitoring & Logging

• Request logs
• Error tracking
• Redis & DB metrics

---

13. Future Enhancements

• Real-time chat (WebSockets)
• Notifications service
• AI-based recommendations
• Mobile app (React Native)

---

14. Conclusion

This application demonstrates a production-ready, scalable full-stack system suitable for public usage. It showcases real-world backend architecture, frontend integration, performance optimization, and security best practices.

---

📌 This document can be used as:

• Project documentation
• Portfolio explanation
• College submission
• Interview discussion material