What a web application firewall is
A web application firewall, or WAF, is a filter that sits between the internet and your application. Every request passes through it first, and the firewall decides whether to let that request continue, challenge it, or block it. Providers like Cloudflare and Akamai run this filtering at the edge of a large network, so suspicious traffic is screened long before it reaches your own server. The goal is to stop common attacks early rather than relying on the application alone to defend itself.
This checker fetches the live response from the URL you enter and looks for the traces a firewall leaves behind. Many WAFs add their own response headers, set distinctive cookies, route traffic through a recognizable edge network, or return challenge and error pages that look a certain way. When enough of those signals line up, we report the firewall and, where we can, name the provider and how confident the match is.
What a WAF does, and what it does not
A WAF is good at filtering. It can block common injection attempts, known malicious payloads, and noisy bad bots, and it can absorb some denial of service pressure at the edge. Treat it as one useful layer of defense, not the whole strategy. Crucially, a firewall does not fix the configuration of the application behind it. It does not add a missing Content-Security-Policy or other security headers, it does not strengthen weak TLS, and it does not set secure flags on your cookies. Those gaps stay open whether or not a WAF is in front of them.
That is the part a firewall cannot cover, and it is where SiteSecurityScore helps. We scan the underlying configuration directly, flag the missing headers, weak TLS, and insecure cookies, and give you copy and paste fixes for your own server. A WAF screens the traffic. Getting the configuration right closes the holes the firewall was never meant to handle.