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The Difference between NGINX App Protect, Azure WAF, and open-appsec WAF

"Good security starts with good design that considers the distributed nature of the application."

When Andrew Hoffman made this quote in his book about web application security, he referred to web application firewalls with a flexible security approach. This flexibility, he says, allows them to accommodate every application's peculiar architecture and behavioral patterns to protect them against attacks effectively.

The open-appsec WAF, Microsoft’s Azure WAF, and NGINX App Protect are three popular web application firewalls with a flexible security approach. They are known to effectively protect web apps against common web attacks and zero-day attacks.

This article contains a detailed description of their features, differences, similarities, and pros and cons to help you decide the best WAF for your web app.

Let’s start with a tabular comparison of the three WAFs.

Comparison Table: NGINX App Protect vs. Azure WAF vs. open-appsec WAF


NGINX App Protect

Azure WAF

open-appsec WAF

Pre-emptive zero-day protection



Employs machine learning algorithms and threat prevention techniques to identify and thwart zero-day attacks and unseen vulnerabilities.

False positives



Low due to ML

Malicious Bot Prevention

It detects and prevents malicious bot attacks by comparing its behavior with the typical user and app behavioral pattern.

It uses the managed bot protection rule to prevent the evasion of malicious bots in your web apps.

Yes, premium (paid) features

Free version

It offers a free 30-day trial.

The cost of the Azure WAF service depends on the pricing tier you choose and the volume of traffic your web application receives.

It is free and also has a paid premium version


It is not open-source.

It is not open-source.

It is open-source, and a third party has independently verified its source code.

WAF community and customer service

It has a large community and readily available resources.

It also has a large community of users.

The open-appsec community is small, so you won't have to wait long for an admin to respond to your message and assist you with any issues you may encounter while using the platform.

Maintenance complexity

Complex system maintenance procedure due to the use of policies and rules.

There’s a complex system maintenance procedure because of its rules, policies, and exclusion list.

Provides easy system maintenance as it doesn’t use threat signatures, rules, and exceptions to protect your web app.

Declarative Configuration




Intrusion Prevention System

Not Available.

Not Available.

Snort 3.0 engine.

Similarities Between Nginx App Protect, Microsoft Azure WAF, and open-appsec WAF

1. They protect against common web attacks, such as SQL injection, cross-site scripting (XSS), and cross-site request forgery (CSRF).

2. They allow for integration with other security tools and DevOps environments.

3. They provide visibility into security events and attacks for monitoring and analysis purposes.

4. All three are designed to be scalable and flexible to accommodate an increase in incoming traffic at any time.

NGINX App Protect Review

This commercial cloud-based web application firewall helps secure your web application from common attacks such as SQL injection, Cross Site Scripting, DDoS attacks, OWASP top 10 attacks, etc. NGINX App Protect can be easily deployed on all DevOps environments as either an on-premises WAF, a cloud-based WAF, or a hybrid WAF, and it can even be containerized.

To ensure the safety of your web app, it acts as a Kubernetes Ingress controller, content cache, web server, software load balance, and API gateway. It uses rules, policies, and auto-learning to monitor, analyze and separate incoming malicious requests from legit ones. To further customize the WAF feature to suit your application's threat factors, NGINX App Protect allows you to block file types, carry out response inspection, HTTP protocol compliance, etc.

One of its most popular features is its effective protection against Denial of Service (DoS) attacks. It does this by evaluating the user behavior (of the incoming request) against a history of requests in the app. This method helps enhance the robustness of web applications and increase efficiency while decreasing the chances of wastage of web app resources.

Another laudable feature of NGINX App Protect is the effective mitigation of common web attacks. It does this by deploying dynamic signatures and using a statistical model to monitor and analyze incoming traffic patterns and block malicious traffic. Not only this, it continuously adapts to the architecture and activities of your web application to further help it guard against unknown vulnerabilities.

Pros and Cons of NGINX App Protect



It can be incorporated into any DevOps environment.

It can take some time for its setup process to complete.

It is reasonably priced and offers a complimentary 30-day trial.

Policy creation and management are done manually and can be time-consuming.

It doesn’t increase web latency.

No pre-emptive zero-day protection

It functions as an efficient reverse proxy.

Microsoft Azure Web Application Firewall Review

Due to the need to effectively protect one's web application against malicious attacks, some people manually encode security measures during app development. While this method might give your web application a more permanent security architecture, it is a rigorous process that requires constant maintenance and update monitoring. To avoid this, Microsoft Azure developed a centralized web application firewall that effectively protects your apps against attacks like SQLi, local and remote file inclusion attacks, XSS, HTTP(S) request smuggling, etc.

This web application firewall can be easily integrated into Azure services, including the Azure Application Gateway, Azure Front Door, and Azure Content Delivery Network.

Listed below are several of its most notable characteristics. The developers of the Azure WAF know that malicious threats start probing your application for vulnerabilities the moment it goes live, so to protect your app, they use policies and rules to monitor and separate incoming malicious traffic from benign traffic.

One of the Azure WAF’s top features is its policies and rules for attack mitigation. It offers rules, policies, and exclusion lists to help tailor your web app’s security. Azure rules are divided into managed rules and custom rules.

The managed rules are pre-configured rules created, maintained, and updated by the Azure security team to help protect your web application against common vulnerabilities. Note that in the case of false positives, you can not disable or modify the setting of a managed rule; however, you are allowed to disable it.

On the other hand, you can use the custom rule to create a more specific security protection that suits your application's purposes. The Azure WAF gives you a chance to reduce the occurrence of false positives by allowing you to create an exclusion list that contains a list of attributes that the web application firewall would ignore while analyzing incoming requests.

Pros and Cons of the Azure Web Application Firewall



It doesn’t take time to deploy.

Its exclusion list is hard to manage.

It best protects web apps when used on Application Gateway.

High level of false positives

It is user-friendly.

No pre-emptive zero-day protection

It does identity validation and load balancing simultaneously and doesn’t increase web latency.

It effectively protects multiple web applications simultaneously.

open-appsec WAF Review

Are you looking for a way to block attacks on your web application before they happen? open-appsec uses machine learning to continuously detect and preemptively block threats before they can do any damage. Our code has also been published on GitHub, and the effectiveness of our WAF has been successfully proven in numerous tests by third parties. Try open-appsec in the Playground today.

The open-appsec WAF is a novel open-source web application firewall that uses machine learning algorithms to monitor, analyze, and block malicious requests. This unique approach to web application security stemmed from the number of false positives and the complex exception handling caused by the rules, policies, and signatures used by other WAFs.

Most contemporary WAFs have an inbuilt security approach (rules, policies, and exceptions) that helps them protect customers' web applications against known attacks. Furthermore, they provide options for their users to modify the said rules to help tailor security to their app's environment.

Notably, this security model has been in place for years because of its efficiency; however, its inability to detect unknown vulnerabilities has caused many web applications to be compromised by zero-day attacks.

To solve this, the open-appsec security team has developed a web application firewall that uses machine learning algorithms to protect your web applications from known and unknown vulnerabilities preemptively.

Here’s How the open-appsec Machine-Learning WAF Approach Works

The open-appsec WAF uses two machine-learning algorithms to monitor incoming traffic and prevent web attacks from accessing your application. These two machine-learning approaches divide the WAF's security process into two stages.

Stage 1

All incoming requests pass through the first machine-learning algorithm - the offline supervised algorithm. This offline algorithm was trained to decipher a malicious request from a legit request using data from millions of requests (both malicious and benign).

This offline ML algorithm analyzes incoming requests and checks for attack indicators (patterns that show that a request is likely to be malicious) to differentiate a malicious request from a legitimate one. After this, it gives the request a confidence score. If it finds the request legitimate, it pushes it to your web app, but if it deems it malicious, it pushes the request to the second stage. Note that the main aim of the first offline machine learning algorithm is to eliminate all chances of false negatives.

Stage 2

The online unsupervised real-time machine learning algorithm carries out this process. Its main task is to eliminate all chances of false positives. And to do this, it takes in all requests likely to be malicious and analyzes them against your app's structure and user behavior. To further analyze these requests, it tests them against factors like user reputation score, payload score, URL score, and parameter score. After its analysis, it blocks the requests or allows them to pass through to your web app.

In general, these two machine learning models not only eliminate the presence of false negatives and false positives, it preemptively protects your web attacks against known and unknown vulnerabilities. Try open-appsec in the Playground today.

Pros and Cons of open-appsec WAF



Simplified system maintenance because it doesn’t use rules, policies, and signatures.

It has a small community.

It uses machine learning to protect your web application against known and unknown vulnerabilities.

Admins can easily declare actions and outcomes using its declarative system configuration.

Our Verdict

Because of its integration with other Azure products, Microsoft Azure is best used to protect applications hosted on the Azure platform. NGINX App Protect, on the other hand, is best known for its flexible deployment options (cloud-based, on-premise, in containers). Finally, open-appsec is popular for its machine-learning algorithms that preemptively detect and block known and unknown exploits. Try open-appsec in the Playground today.

Frequently asked questions

Can NGINX App Protect be called a WAF?

Yes, NGINX App Protect can be considered a Web Application Firewall (WAF) because it sits between a web application and the internet, protecting the application from malicious traffic.

What is the difference between Application Gateway WAF and Azure Firewall?

Application Gateway Web Application Firewall (WAF) is a layer 7 firewall specifically designed to provide centralized protection for web applications hosted in Azure. Inversely, Azure Firewall is a centralized network security that operates at layers 3 and 4 and protects your network traffic.

Is NGINX WAF free?

NGINX is open-source software and can be used for free, but some NGINX modules, such as the NGINX WAF module, may require a paid license. It's best to check with the vendor or consult the relevant documentation to determine the cost and licensing options for any specific NGINX modules you want to use.

Is Azure WAF any good?

Azure Web Application Firewall (WAF) helps protect web applications from various security threats. It is considered a good web application security solution, as it offers a range of features and benefits such as scalability, effective bot mitigation, integration with Azure services, etc.


Experiment with open-appsec for Linux, Kubernetes or Kong using a free virtual lab

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