What is a cloud web application firewall (WAF)?

A Web Application Firewall (WAF) sits between a web application and incoming internet traffic, filtering and monitoring HTTP/HTTPS requests before they reach the application. Its primary job is to detect and block malicious traffic targeting the application layer, including SQL injection, cross-site scripting (XSS), file inclusion attacks, and other exploits.

Traditional network firewalls operate at the network and transport layers. They control access between systems but have no visibility into what happens inside web application traffic. A WAF fills that gap. It reads and interprets web requests in context, identifying attack patterns and blocking them in real time without disrupting legitimate users.

Web Application Firewall (WAF) can be deployed in three ways:

• As hardware appliances on-premises
• As software integrated into the application environment, or
• As cloud-based solutions sitting in front of the application

Cloud-based WAFs are increasingly common for enterprises running distributed architectures, as they scale without infrastructure overhead and can be updated with new threat signatures quickly.

Beyond blocking attacks, WAFs also help with rate limiting, bot mitigation, and geo-blocking, giving security teams broader control over who accesses their applications and how. For enterprises handling sensitive customer data, financial transactions, or regulated workloads, a WAF is a foundational control within any serious application security posture.