Storing JWT tokens in localStorage has become a serious security risk because XSS attacks can steal them, so developers should adopt safer alternatives such as HttpOnly cookies, BFF‑backed sessions, or Service Worker‑based in‑memory storage, each with its own trade‑offs.
Storing JWT tokens in localStorage, once a common practice for front‑end authentication, now poses severe XSS risks, prompting developers to adopt more secure methods such as HttpOnly cookies with SameSite protection, BFF‑backed session cookies, or Service Worker‑based token handling, each with trade‑offs.
This article explains what Cross‑Site Scripting (XSS) is, describes its various types and the severe threats it poses, and provides comprehensive defense techniques—including input/output validation, HTML/JavaScript encoding, HttpOnly cookies, and secure handling of URLs, CSS, and rich‑text content—to protect web applications from XSS attacks.
