backend-technologies

name	backend-technologies
description	Master backend development with REST APIs, databases, authentication, and server frameworks. Use when building APIs, working with databases, or implementing backend logic.

Backend Technologies Skill

Comprehensive guide to backend development and API design.

Quick Start

REST API with Express.js

const express = require('express');
const app = express();

app.use(express.json());

// GET endpoint
app.get('/api/users/:id', (req, res) => {
  const { id } = req.params;
  res.json({ id, name: 'John Doe' });
});

// POST endpoint
app.post('/api/users', (req, res) => {
  const user = req.body;
  res.status(201).json(user);
});

// Error handling
app.use((err, req, res, next) => {
  res.status(500).json({ error: err.message });
});

app.listen(3000, () => {
  console.log('Server running on port 3000');
});

Database Query (PostgreSQL)

-- Create table
CREATE TABLE users (
  id SERIAL PRIMARY KEY,
  name VARCHAR(255) NOT NULL,
  email VARCHAR(255) UNIQUE NOT NULL,
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

-- Query with joins
SELECT u.name, COUNT(p.id) as post_count
FROM users u
LEFT JOIN posts p ON u.id = p.user_id
GROUP BY u.id
ORDER BY post_count DESC;

-- Transactions
BEGIN;
UPDATE accounts SET balance = balance - 100 WHERE id = 1;
UPDATE accounts SET balance = balance + 100 WHERE id = 2;
COMMIT;

Authentication with JWT

const jwt = require('jsonwebtoken');

// Generate token
function generateToken(userId) {
  return jwt.sign(
    { userId },
    process.env.JWT_SECRET,
    { expiresIn: '24h' }
  );
}

// Verify token middleware
function authMiddleware(req, res, next) {
  const token = req.headers.authorization?.split(' ')[1];

  try {
    const decoded = jwt.verify(token, process.env.JWT_SECRET);
    req.userId = decoded.userId;
    next();
  } catch (error) {
    res.status(401).json({ error: 'Invalid token' });
  }
}

Key Concepts

API Design

• RESTful principles
• Resource-oriented URLs
• Proper HTTP methods and status codes
• Request/response format (JSON)
• Versioning strategies
• Rate limiting
• Error handling

Database Design

• Normalization and relationships
• Indexes for performance
• Transactions and ACID properties
• Query optimization
• Connection pooling
• Migrations and schema versioning

Security

• Input validation and sanitization
• SQL injection prevention
• CORS configuration
• Rate limiting
• Helmet middleware for headers
• Secure password hashing
• Environment variables for secrets

Performance

• Caching strategies (Redis)
• Query optimization
• Database indexes
• Connection pooling
• Async/await patterns
• Load testing

Popular Frameworks

Node.js

• Express: Minimal web framework
• Fastify: High-performance alternative
• NestJS: Full-featured framework with TypeScript
• Koa: Lightweight successor to Express

Python

• Flask: Lightweight microframework
• Django: Full-featured web framework
• FastAPI: Modern async framework
• SQLAlchemy: ORM library

Java

• Spring Boot: Enterprise-grade framework
• Quarkus: Cloud-native alternative
• Micronaut: Lightweight framework

Go

• Gin: Web framework
• Echo: High-performance framework
• Fiber: Express-inspired framework

Tools & Libraries

ORMs & Query Builders

• Prisma: Next-gen ORM
• Sequelize: Promise-based ORM
• TypeORM: ORM for TypeScript
• SQLAlchemy: Python ORM

Testing

• Jest: Test framework
• Supertest: HTTP assertion library
• Mocha: Test runner
• Pytest: Python testing

API Documentation

• Swagger/OpenAPI
• Postman
• Insomnia

Resources

• REST API Best Practices
• Node.js Documentation
• PostgreSQL Documentation
• API Design Checklist