Comprehensive security hardening for web applications covering HTTPS, input validation, authentication, and OWASP Top 10 vulnerabilities.

• Enforces HTTPS, security headers (CSP, HSTS), and rate limiting via Helmet and Express middleware to prevent DDoS and common attacks
• Prevents SQL Injection and XSS through parameterized queries, input validation with Joi, and output encoding with DOMPurify
• Implements CSRF token protection, JWT-based authentication with refresh token rotation, and secret management via environment variables
• Includes OWASP Top 10 checklist and best practices for access control, defense in depth, and principle of least privilege