The core problem is that most security tools protect the server, but client-side attacks happen in the browser where those tools have no visibility. Ecommerce teams often discover skimming through customer complaints rather than their own alerts. When teams do deploy client-side tools, they frequently run into CSP limitations, because CSPs block by origin rather than by behaviour, so a compromised script served from an already-approved domain bypasses them entirely. The result is either a false sense of coverage or alert noise that teams stop acting on.
How do client-side attacks actually happen?
Compromising a third-party service your website relies on is one common way attackers get in.
Why can't traditional security tools detect client-side threats?
Firewalls, WAFs, and vulnerability scanners are traditional security tools used to protect your server, but they cannot see what's happening in your users' browsers.
What's the difference between client-side security and server-side security?
Server-side security protects your infrastructure, while client-side security focuses on where your application actually runs, inside your users' browsers.
What's the difference between client-side security and application security?
Client-side security is a critical subset of AppSec that focuses on protecting applications where they actually execute--in users' browsers.