ModSecurity and OWASP CRS helped define open source web application firewalls (WAFs). Yet their reliance on static rules, manual tuning, and regular maintenance makes them hard to manage in fast-paced environments. In modern infrastructures, these WAFs often force a trade-off between security, performance, and complexity, which is no longer sustainable.
A WAF Built for Modern Infrastructure
The CrowdSec WAF is different. It is open source, behavior-driven, and powered by collaboration. It analyzes live behaviors, not just patterns, and adapts instantly. Its detection logic is enriched by real-world signals collected from a global network of deployments.
Moreover, the CrowdSec WAF works out of band. It observes HTTP traffic from your existing infrastructure, whether it is in the cloud, on-premises, or within containers. There is no need to re-architect your application stack or worry about performance bottlenecks. It scales naturally with your infrastructure and plays well with automation and CI/CD pipelines.
Read more about how Websupport uses the CrowdSec WAF as a modern replacement.
Proactive Security, Not Reactive Patching
Most WAFs react. CrowdSec anticipates.
Its detection scenarios are designed to recognize behaviors that lead to exploitation. You can benefit from virtual patching without lifting a finger. CrowdSec keeps your applications protected even before official CVE patches are available.
Out of the box, CrowdSec WAF includes high-quality IP reputation data built from real attack signals. This allows you to block known bad actors preemptively, cut resource usage, and filter out internet noise that clutters logs and triggers alert fatigue.
A WAF that Grows Smarter with Others
Every CrowdSec user contributes to a live map of attacker activity. Each deployment shares anonymized metadata about attacks, including the time they occurred, the responsible party, and the observed behavior. No logs or private data are ever exposed.
These shared signals power a real-time threat intelligence network. When one CrowdSec user sees an attack, everyone else is protected. This is a community-driven model in which every participant strengthens the whole.
Transparent by Design
CrowdSec is fully open source under the MIT license. You can audit the code and contribute improvements. There are no black boxes. You are not waiting for a vendor to issue updates. The community moves quickly and responds in real time.
This transparency is not just about code. It is about trust. You verify everything CrowdSec does and shape how it evolves.
A Smarter Path from ModSecurity WAF
No need to throw everything away if you already use ModSecurity. CrowdSec supports existing ModSecurity rules. You can import your current configurations and test them out of band, in a non-intrusive way. This lets you reduce false positives, simplify rule management, and transition at your own pace.
You keep what works. CrowdSec improves the rest. It is more than just a WAF, it is a growing defense network that gets stronger with every new signal. While it helps you protect your applications today, it also prepares you for the threats of tomorrow.
How to Get Started with the CrowdSec Web Application Firewall
Here is a brief look at how the CrowdSec WAF works technically:
- First, the Web Server receives the HTTP request.
- Next, the HTTP Request is intercepted and passed to the CrowdSec Security Engine via the HTTP API.
- The Security Engine answers to the Web Server once the Appsec in-band rules have been processed.
- Finally, based on the Security Engine’s answer, the Web Server either blocks the HTTP Request or processes it as usual.
Deploying the CrowdSec WAF can be done simply by following the guide provided on our document webpage or by following the video shown below.
Don’t just run a WAF. Join a defense network.
