Module 10 · 1 chapters

Frontend Security

Frontend security is no longer optional — SDE-2 interviews expect you to explain XSS types, CSRF prevention, JWT storage trade-offs, CSP headers, and why localStorage is dangerous for tokens.

This module covers the top 10 frontend security risks, prevention patterns with code examples, security headers, best practices, and the testing tools every engineer should know.

Security is a design constraint, not an afterthought — you will learn to threat-model auth flows, sanitize user HTML safely, configure CSP without breaking the app, and audit dependencies before they reach production.

Walk through XSS variants, CSRF token patterns, JWT storage in httpOnly cookies, SSRF and IDOR risks, CORS misconfiguration, CSP directives, and npm audit workflows with prevention code you can cite in interviews.

Chapters in this module

  1. Frontend SecurityClient-side security for web apps: XSS (stored, reflected, DOM-based), CSRF, SSRF, IDOR, authentication attacks, JWT best practices, SQL injection, CORS, insecure dependencies, sensitive data exposure, CSP, and security headers.
Start with Frontend Security