Frontend Architecture & System Design

ReactJS - Complete Architecture

Step-by-step guide to ReactJS architecture: component design, state management, hooks, routing, and performance optimization for production applications.

Component Architecture

Component Types

Functional Components: Modern approach using Hooks API, cleaner syntax
Class Components: Legacy approach, lifecycle methods, this binding
Higher-Order Components: Reuse component logic, wrapper pattern
Render Props: Share code via render functions as props
Compound Components: Related components working together

Component Patterns

Container/Presentational: Separation of logic and UI
Atomic Design: Atoms → Molecules → Organisms → Templates
Composition Pattern: Build complex UIs from simple components
Custom Hooks: Extract and share stateful logic
Context Pattern: Global state without prop drilling

State Management Strategies

useState Hook

Local component state management for simple state

• Simple state updates
• Functional updates
• Lazy initialization

useReducer Hook

Complex state logic with reducer pattern

• Multiple state values
• Predictable updates
• Action-based updates

Context API

Global state without prop drilling

• Provider/Consumer pattern
• Multiple contexts
• Performance optimization

React Hooks API

useState

Component state management, returns [state, setState]

useEffect

Side effects, lifecycle, cleanup functions

useContext

Consume React Context values

useReducer

Complex state with reducer pattern

useMemo

Memoize expensive calculations

useCallback

Memoize callback functions

useRef

Mutable references, DOM access

Custom Hooks

Reusable stateful logic extraction

Performance Optimization

React.memo()

Prevent unnecessary re-renders by memoizing components

const MemoizedComponent = React.memo(Component);

Code Splitting

Lazy loading components with React.lazy() and Suspense

const LazyComponent = React.lazy(() => import('./Component'));

Virtual DOM

Efficient DOM updates through diffing algorithm

• Diffing algorithm
• Batch updates
• Reconciliation

Memoization

Optimize expensive calculations with useMemo & useCallback

• useMemo for values
• useCallback for functions
• Dependency arrays

ReactJS Best Practices

Component Design

Keep components small and focused
Use composition over inheritance
Extract reusable logic to custom hooks
Use PropTypes or TypeScript for type safety

Performance Tips

Memoize expensive calculations
Use React.memo for pure components
Implement code splitting for large apps
Optimize re-renders with proper dependencies

Complete ReactJS System Architecture

ReactJS Architecture Flow Diagram

Users

Web, Mobile Browsers

Browser

DOM, Events

CDN

Static Assets

React Core

Virtual DOM, Reconciliation

Functional

Components

Hooks, JSX

Component

Tree

Hierarchy

Custom

Hooks

Reusable Logic

HOCs

Patterns

Composition

Context API

Global State

Provider Pattern

Local State

useState

useReducer

Redux/Zustand

External Store

State Library

useEffect

Side Effects

useMemo

Memoization

useCallback

Function Cache

API Client

Axios, Fetch

HTTP Requests

React Query

SWR, TanStack

Data Fetching

React Router

Client-side Routing

Navigation

REST API

Backend Services

GraphQL

Query Language

WebSocket

Real-time

ReactJS Technology Stack

Core Libraries

• React 18+ (Core)
• React DOM
• React Router
• React Hooks

State Management

• Context API
• Redux Toolkit
• Zustand
• Jotai

Build Tools

• Create React App
• Vite
• Webpack
• Babel

Component Hierarchy & Design Patterns

React Component Hierarchy:

                            App (Root Component)

                            ├── Layout # App structure

                            │   ├── Header # Navigation

                            │   ├── Sidebar # Menu

                            │   └── Main # Content area

                            │       ├── Dashboard # Feature

                            │       │   ├── StatsCard # UI Component

                            │       │   └── Chart # UI Component

                            │       └── Profile # Feature

Container/Presentational

Separation of logic and UI

Compound Components

Related components working together

Render Props

Share code via render functions

ReactJS State Management Architecture

Local State (useState)

Component-level state management

const [count, setCount] = useState(0);

Global State (Context API)

App-wide state without prop drilling

const value = useContext(AppContext);

ReactJS API Integration Approach

REST API Integration

• Axios for HTTP requests
• Fetch API
• Custom hooks for data fetching
• Error handling & retry logic

Data Fetching Patterns

• useEffect for side effects
• Custom hooks (useFetch, useAPI)
• React Query / SWR
• Loading & error states

ReactJS Build & Deployment

Build Process

• npm run build (production)
• Code splitting & lazy loading
• Minification & optimization
• Tree shaking

Deployment Options

• Static hosting (Netlify, Vercel)
• CDN deployment
• Docker containerization
• CI/CD pipelines

NextJS - Complete Architecture

Complete NextJS architecture walkthrough: App Router implementation, Server Components, rendering strategies, API routes, and deployment configurations.

App Router Architecture (Next.js 13+)

Directory Structure:

                            app/

                            ├── layout.tsx # Root layout with providers

                            ├── page.tsx # Home page (Server Component)

                            ├── loading.tsx # Loading UI

                            ├── error.tsx # Error boundary

                            ├── dashboard/ # Route segment

                            │   ├── layout.tsx # Nested layout

                            │   ├── page.tsx # Dashboard page

                            │   └── loading.tsx # Route-level loading

                            └── api/ # API routes

                                └── users/route.ts # API endpoint

Server Components

Default in App Router - zero client JS
Direct database access
Faster initial page load
Better SEO performance

Client Components

'use client' directive required
Interactive UI elements
State management (useState, useEffect)
Browser APIs access

Rendering Strategies

SSR (Server-Side Rendering)

Render pages on each request

• Dynamic content
• Real-time data
• User-specific pages

SSG (Static Site Generation)

Pre-render pages at build time

• Fastest performance
• CDN-friendly
• SEO optimized

ISR (Incremental Static Regeneration)

Update static pages on-demand

• Best of both worlds
• Revalidate intervals
• On-demand revalidation

API Routes & Server Actions

API Routes

Serverless functions for backend logic

                                // app/api/users/route.ts

                                export async function GET() {

                                  const users = await db.query('SELECT * FROM users');

                                  return Response.json(users);

                                }

• RESTful endpoints (GET, POST, PUT, DELETE)
• Serverless functions
• Direct database access

Server Actions

Type-safe server mutations

                                // app/actions.ts

                                'use server'

                                export async function createUser(data) {

                                  await db.users.create(data);

                                }

• Form submissions
• Progressive enhancement
• Type-safe with TypeScript

Built-in Performance Optimizations

Image Optimization

Automatic format conversion (WebP, AVIF), lazy loading, responsive images

                                <Image src="/image.jpg"

                                  width={800} height={600}

                                  alt="Description"

                                />

Font Optimization

Automatic font subsetting, preloading, display swap

                                import { Inter } from 'next/font/google';

                                const inter = Inter({ subsets: ['latin'] });

Code Splitting

Automatic route-based code splitting, dynamic imports

• Route-based splitting
• Dynamic imports
• Tree shaking

Edge Runtime

Deploy API routes and middleware at the edge

export const runtime = 'edge';

NextJS Best Practices

Server Components First

Use Server Components by default
Only use 'use client' when needed
Fetch data in Server Components

Performance Tips

Use Next.js Image component
Implement ISR for dynamic content
Optimize bundle size

Complete NextJS System Architecture

NextJS Architecture Flow Diagram

Users

Web, Mobile Browsers

CDN & Edge

Static Assets, Caching, Global Distribution

Next.js Framework

App Router, React 19, TypeScript

App Router

File-based

Routing

Layouts

Nested

Structure

Pages

Route

Handlers

API Routes

Serverless

Functions

Server Components

Zero Client JS

Direct DB Access

Client Components

Interactive UI

'use client'

Server Actions

Type-safe

Mutations

SSR

Server-Side

Rendering

SSG

Static Site

Generation

ISR

Incremental

Regeneration

Edge

Edge Runtime

Functions

State Management

Context API

Zustand, Jotai

Data Fetching

Server Components

Direct DB Queries

Caching

Request Cache

Full Route Cache

Image Opt

WebP, AVIF

Font Opt

Subsetting

Code Split

Tree Shaking

Backend API

FastAPI Services

PostgreSQL

Direct Queries

Redis

Cache, Sessions

NextJS Technology Stack

Core Framework

• Next.js 16 (App Router)
• React 19
• TypeScript
• Node.js Runtime

Styling & UI

• Tailwind CSS
• CSS Modules
• Styled Components
• Shadcn/ui

Data & State

• Server Components
• Server Actions
• React Query
• Context API

NextJS Component Architecture & System Design

App Router Structure:

                            app/

                            ├── layout.tsx # Root layout

                            ├── page.tsx # Home page

                            ├── loading.tsx # Loading UI

                            ├── error.tsx # Error boundary

                            └── dashboard/ # Route segment

                                ├── layout.tsx # Nested layout

                                └── page.tsx # Dashboard page

Component Hierarchy & Design Patterns

Layout Pattern

Nested layouts for shared UI

Server/Client Split

Optimal component placement

Parallel Routes

Simultaneous route rendering

NextJS State Management

Server State

• Server Components (default)
• Direct database access
• Server Actions
• API Routes

Client State

• useState, useReducer
• Context API
• Zustand / Jotai
• React Query

NextJS API Integration

Server Components

• Direct database queries
• Server-side data fetching
• Zero client JavaScript
• Automatic caching

API Routes

• RESTful endpoints
• Serverless functions
• External API integration
• Middleware support

NextJS Build & Deployment

Build Process

• next build (optimized)
• Static & dynamic generation
• Image optimization
• Font optimization

Deployment Options

• Vercel (recommended)
• Docker containerization
• Node.js servers
• Static export

Django - Complete Architecture

A comprehensive guide to Django framework including ORM, Views, Templates, Admin Panel, REST Framework, and security features.

Models & ORM

Django ORM

Database abstraction layer for Python

                                class User(models.Model):

                                  name = models.CharField(max_length=100)

                                  email = models.EmailField()

                                  created_at = models.DateTimeField(auto_now_add=True)

Database abstraction
Query optimization (select_related, prefetch_related)
Relationships (ForeignKey, ManyToMany, OneToOne)

Model Features

Field Types: CharField, IntegerField, DateTimeField, JSONField, etc.
Validators: Built-in and custom validation
Model Methods: __str__, save(), get_absolute_url()
Meta Options: Ordering, verbose names, indexes
Signals: pre_save, post_save, pre_delete

Views & Templates

Function Views

Simple request/response handlers

                                def user_list(request):

                                  users = User.objects.all()

                                  return render(request, 'users.html', {'users': users})

Class-Based Views

Reusable view classes with mixins

                                class UserListView(ListView):

                                  model = User

                                  template_name = 'users.html'

Template System

Django templates with inheritance

• Template inheritance
• Template tags & filters
• Context processors

Django Admin Panel

Automatic admin interface for model management

                            @admin.register(User)

                            class UserAdmin(admin.ModelAdmin):

                              list_display = ['name', 'email', 'created_at']

                              search_fields = ['name', 'email']

                              list_filter = ['created_at']

ModelAdmin: Custom admin interface

InlineAdmin: Nested editing

Admin Actions: Bulk operations

Custom Views: Extended functionality

Django REST Framework

Serializers

Convert complex data types to/from Python native types

                                class UserSerializer(serializers.ModelSerializer):

                                  class Meta:

                                    model = User

                                    fields = '__all__'

• Model serializers
• Nested serializers
• Field validation
• Custom fields

ViewSets & Routers

Powerful abstractions for building REST APIs

                                class UserViewSet(viewsets.ModelViewSet):

                                  queryset = User.objects.all()

                                  serializer_class = UserSerializer

• ModelViewSet (CRUD)
• ReadOnlyViewSet
• Custom actions (@action)
• Automatic URL routing

Security Features & Middleware

Built-in Security

CSRF Protection: Cross-Site Request Forgery tokens
XSS Prevention: Automatic template escaping
SQL Injection: ORM parameterized queries
Password Hashing: PBKDF2, bcrypt, argon2

Middleware System

Authentication: User authentication middleware
Security Headers: X-Frame-Options, CSP, HSTS
Custom Middleware: Request/response processing
Session Management: Secure session handling

Django Best Practices

Project Structure

Separate apps for features
Reusable apps
Settings per environment

Performance Tips

Use select_related and prefetch_related
Database indexing
Caching strategies

Complete Django System Architecture

Django MVT Architecture Flow Diagram

Users

Web Browsers, API Clients

Load Balancer

Nginx

WSGI Server

Gunicorn, uWSGI

Django Framework

Python Web Framework

Security

CSRF, XSS

Authentication

Session, Auth

Common

Headers, Logging

Custom

Middleware

URL Dispatcher

URL Patterns, Regex

Reverse URLs

Model

Django ORM

Database Abstraction

Migrations, Queries

View

Function/Class Views

Business Logic

Request Handling

Template

Django Templates

HTML Rendering

Template Tags

Admin Panel

Model Management

Auto-generated

REST Framework

ViewSets, Serializers

API Endpoints

Celery

Task Queue

Async Tasks

PostgreSQL

Primary Database

ORM Queries

Redis

Cache, Sessions

Message Broker

File Storage

GCS, S3

Media Files

Django Technology Stack

Core Framework

• Django 4.x
• Python 3.10+
• Django REST Framework
• Django Channels (WebSocket)

Database & ORM

• PostgreSQL
• MySQL / SQLite
• Django ORM
• Database migrations

Additional Tools

• Celery (async tasks)
• Redis (caching)
• Gunicorn (WSGI)
• Nginx (reverse proxy)

Django Component Architecture

Project Structure:

                            project/

                            ├── manage.py

                            ├── settings.py # Configuration

                            ├── urls.py # URL routing

                            ├── wsgi.py # WSGI config

                            └── apps/ # Django apps

                                ├── users/ # User app

                                │   ├── models.py # Models

                                │   ├── views.py # Views

                                │   └── urls.py # App URLs

Django Design Patterns

MVT Pattern

Model-View-Template separation

Class-Based Views

Reusable view classes

Mixins

Code reuse via mixins

Django State Management

Session Management

• Django sessions
• Cookie-based sessions
• Database sessions
• Cache sessions

Context Data

• Template context
• Context processors
• Request context
• View context

Django API Integration

Django REST Framework

• ViewSets & Routers
• Serializers
• Authentication & Permissions
• API versioning

Direct Database Access

• Django ORM queries
• Raw SQL queries
• Database transactions
• Query optimization

Django Build & Deployment

Build Process

• collectstatic (static files)
• migrate (database)
• collectstatic optimization
• Environment configuration

Deployment Options

• Gunicorn + Nginx
• Docker containerization
• AWS / GCP / Azure
• Heroku / Railway

API Integration Strategy

Strategic API integration approach combining RESTful backend services with optimized data fetching patterns for scalable frontend applications.

Hybrid API Integration Approach

Best of both worlds: Security & Performance

Backend API Integration

Secure, business-logic-driven API calls via FastAPI backend

Authentication: Login, signup, OTP via FastAPI backend
User Management: Profile, settings, preferences
Business Logic: Complex operations and data processing
Payment Processing: Secure payment transactions

Direct Database Access

High-performance direct queries for read-heavy operations

Analytics Queries: Fast dashboard data retrieval
Read Operations: List ads, analytics, reports
Performance: Reduced latency, faster queries
Security: Server-side only, no client exposure

Integration Flow Architecture

                                        POST /auth/login-with-password
                                    
                                        FastAPI Backend
                                    
                                        JWT Token
                                    
                                        GET /api/ads/analytics/summary
                                    
                                        Next.js API Route
                                    
                                        PostgreSQL
                                    
                                        Response

API Client Architecture

Robust request/response handling with interceptors

Request Interceptors

Automatic token injection
Request logging
Error handling setup
Content-type headers
Base URL configuration

Response Interceptors

Token refresh on expiry
Error response handling
Response transformation
Success/error logging
Automatic retry logic

Error Handling

Centralized error handling
User-friendly messages
Retry mechanisms
Network error detection
Error boundary integration

Token Management

Secure token storage
Automatic token refresh
Token expiration handling
Logout on invalid token
Multi-tab synchronization

UI/UX Design System

A comprehensive design system ensuring consistency, accessibility, and exceptional user experiences across all platforms.

Design Principles & Patterns

Foundation of exceptional user experiences

Mobile-First

Responsive breakpoints
Touch-friendly interfaces
Adaptive layouts
Progressive enhancement

Design Consistency

Unified color system
Typography scale
Spacing system
Component library

Performance

Optimized images
Code splitting
Lazy loading
Minimal bundle size

Accessibility

WCAG 2.1 compliance
Keyboard navigation
Screen reader support
ARIA labels

Dark Mode

System preference detection
Manual toggle
Persistent preference
Smooth transitions

Internationalization

Multi-language support
RTL language support
Currency switching
Locale-based formatting

Component Library & Reusability

Reusable, type-safe components for rapid development

Core Components

DashboardNav

Navigation

ProtectedRoute

Security

LanguageSwitcher

i18n

CurrencySwitcher

Localization

Component Features

TypeScript Interfaces: Type-safe props and state
Composition: Flexible component composition
Customization: Props for styling and behavior
Error Boundaries: Graceful error handling
Loading States: Skeleton screens and spinners
Accessibility: ARIA labels and keyboard support

Performance Optimization

Advanced optimization techniques ensuring lightning-fast load times and exceptional user experiences.

Optimization Strategies

Code Splitting: Automatic route-based splitting, dynamic imports for heavy components
Image Optimization: Next.js Image component with automatic format conversion, lazy loading, responsive images
Font Optimization: Next.js font optimization with subsetting, preloading, and display swap
Server-Side Rendering: Pre-rendered pages for faster initial load and better SEO
Static Generation: Pre-built static pages for maximum performance
Bundle Optimization: Tree shaking, minification, compression

Caching Strategies

Browser Caching: Static assets cached with long expiration
CDN Caching: Edge caching for global content delivery
API Response Caching: Server-side caching for API routes
React Query: Client-side data caching and synchronization
Service Workers: Offline support and background sync
ISR (Incremental Static Regeneration): On-demand page regeneration

Performance Metrics

95+

Lighthouse Score

<2s

Time to Interactive

<1s

First Contentful Paint

<500KB

Initial Bundle Size

Frontend Security Architecture

Client-Side Security Measures

Authentication Security

JWT Storage: Secure httpOnly cookies or localStorage with encryption
Token Refresh: Automatic token refresh before expiration
Protected Routes: Route guards and authentication checks
Session Management: Automatic logout on token expiry

Input Validation

Client-Side Validation: Immediate feedback for users
XSS Prevention: React's automatic escaping
CSRF Protection: Token-based request validation
Sanitization: Input sanitization before submission

Content Security

CSP Headers: Content Security Policy enforcement
HTTPS Only: Secure connections enforced
Secure Cookies: HttpOnly, Secure, SameSite flags
Environment Variables: Sensitive data in env vars only

Error Handling

Error Boundaries: Graceful error handling
Error Messages: No sensitive data exposure
Logging: Client-side error tracking
Fallback UI: User-friendly error pages

System Design Patterns & Best Practices

Proven architectural patterns and best practices for building scalable, maintainable, and performant frontend applications.

Architectural Design Patterns

Foundation of scalable frontend architecture

Component Composition

Composition over Inheritance: Flexible component composition using props and children
Render Props: Share code between components using render functions
Higher-Order Components: Reuse component logic across multiple components
Custom Hooks: Extract and share stateful logic between components

State Management Patterns

Context API: Global state management without prop drilling
Reducer Pattern: Complex state logic with useReducer hook
Server State: Separate server and client state management
Optimistic Updates: Immediate UI updates before server confirmation

Data Fetching Patterns

Server Components: Fetch data directly in server components
API Routes: Server-side data processing and transformation
Parallel Data Fetching: Fetch multiple data sources simultaneously
Streaming SSR: Progressive page rendering with Suspense

Error Handling Patterns

Error Boundaries: Catch and handle React component errors
Try-Catch Blocks: Handle async errors in useEffect and event handlers
Fallback UI: Graceful degradation with error states
Error Logging: Centralized error tracking and reporting

Performance Optimization Patterns

Advanced techniques for optimal performance

Code Splitting

Route-based splitting
Dynamic imports
Component lazy loading
Library splitting

Memoization

React.memo()
useMemo() hook
useCallback() hook
Memoized selectors

Virtualization

List virtualization
Window scrolling
Infinite scroll
Pagination

Prefetching

Link prefetching
Data prefetching
Image prefetching
Route prefetching

Debouncing

Search input
Scroll events
Resize events
API calls

Throttling

Scroll handlers
Mouse events
Window resize
Animation frames

Scalability & Maintainability Patterns

Building for growth and long-term success

Project Structure

Feature-Based Organization: Group related files by feature
Barrel Exports: Centralized exports for cleaner imports
Shared Utilities: Common functions in lib directory
Type Definitions: Centralized TypeScript types

Development Practices

TypeScript: Type safety and better IDE support
ESLint: Code quality and consistency
Prettier: Automated code formatting
Git Hooks: Pre-commit validation and formatting

Backend Integration Patterns

Seamless connection between frontend and backend

Hybrid Integration Strategy

Backend API (FastAPI)

Used for: Authentication, AI services, Payment processing, User management

Benefits: Security, business logic, complex operations

Direct Database (PostgreSQL)

Used for: Analytics queries, Dashboard data, Read-heavy operations

Benefits: Performance, reduced latency, direct access

API Client Pattern

Centralized API client
Request interceptors
Response interceptors
Error handling

Server Actions

Form submissions
Mutations
Server-side logic
Progressive enhancement

API Routes

Server-side endpoints
Database queries
Data transformation
Caching layer

Frontend Architecture Overview

Component-Based

Performance

Responsive

Frontend Architecture Flow

Technology Stack

ReactJS - Complete Architecture

Component Architecture

Component Types

Component Patterns

State Management Strategies

useState Hook

useReducer Hook

Context API

React Hooks API

useState

useEffect

useContext

useReducer

useMemo

useCallback

useRef

Custom Hooks

Performance Optimization

React.memo()

Code Splitting

Virtual DOM

Memoization

ReactJS Best Practices

Component Design

Performance Tips

Complete ReactJS System Architecture

ReactJS Architecture Flow Diagram

ReactJS Technology Stack

Core Libraries

State Management

Build Tools

Component Hierarchy & Design Patterns

React Component Hierarchy:

Container/Presentational

Compound Components

Render Props

ReactJS State Management Architecture

Local State (useState)

Global State (Context API)

ReactJS API Integration Approach

REST API Integration

Data Fetching Patterns

ReactJS Build & Deployment

Build Process

Deployment Options

NextJS - Complete Architecture

App Router Architecture (Next.js 13+)

Directory Structure:

Server Components

Client Components

Rendering Strategies

SSR (Server-Side Rendering)

SSG (Static Site Generation)

ISR (Incremental Static Regeneration)

API Routes & Server Actions

API Routes

Server Actions

Built-in Performance Optimizations

Image Optimization

Font Optimization

Code Splitting

Edge Runtime

NextJS Best Practices

Server Components First

Performance Tips

Complete NextJS System Architecture

NextJS Architecture Flow Diagram

NextJS Technology Stack

Core Framework

Styling & UI

Data & State

NextJS Component Architecture & System Design

App Router Structure:

Component Hierarchy & Design Patterns