What Is a WAF (Web Application Firewall) and Do You Need One?

A Web Application Firewall sits between the internet and your website, inspecting incoming HTTP requests and blocking ones that look like known attack patterns before they ever reach your actual application code.

What a WAF Typically Catches

Common WAF rules block obvious SQL injection payloads, cross-site scripting attempts, known bad bot signatures, and abusive traffic patterns like a single IP hammering a login endpoint. Providers like Cloudflare, Sucuri, and AWS WAF ship with large rule sets covering these patterns out of the box.

What a WAF Doesn't Do

A WAF is a filter, not a fix. It doesn't patch a vulnerable dependency, doesn't correct a logic flaw in your application, and can be bypassed by a sufficiently unusual attack payload that doesn't match its known patterns. It reduces exposure — it doesn't replace fixing the underlying issue.

Signs a Site Already Has One

Unusual response headers, a distinctive block page when you send a deliberately malformed request, or unexplained CAPTCHAs on normal traffic are all common signs a WAF is active. Many site owners inherit a WAF through their CDN without realizing it's there — or, just as often, assume they have one when they don't.

Check What's Protecting a Site

Nexora Shield's WAF Detector fingerprints response headers and behavior to identify which WAF or CDN security layer, if any, is in front of a given website.