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Unveiling the 13 Best Web Application Firewall (WAF) Solution

The head of security Analytics at Vectra AI, Chris Morales, once pointed out expertly, “Deploying a web application without a firewall is like leaving your front door open in a high-crime neighborhood. You're just asking for trouble”.

The quote perfectly summarizes the importance of a Web Application Firewall (WAF). To ensure your safety, one of the most important tasks is determining the best WAF that won't cost an arm and a leg but will protect your web app from known and unknown attacks.

This article contains an overview of the most popular WAF options, including factors that’ll help you determine if they’re a good fit for your startup, small business, or large organization. We’ll discuss a general overview of each WAF, its key features, pricing, pros, and cons.

Let’s get the ball rolling.

Top WAF Solutions of All Time

open-appsec Web Application Firewall by open-appsec

Are you looking for a way to block web attacks on your web apps before they happen? One option is open-appsec which uses two machine learning algorithms to continuously detect and preemptively block threats before they can do any damage. It protects your web application from both known and unknown vulnerabilities.

Importantly, the two machine learning algorithms consist of an offline and online algorithm. The supervised offline algorithm has been trained in millions of malicious and legitimate requests and can spot attack indicators in incoming requests. It pushes suspicious requests to the second algorithm and allows non-suspicious requests to access your web server.

As for the second algorithm, it is online and unsupervised. Its job is to reduce the chances of false positives by re-analyzing all suspicious requests sent by the offline algorithm against learned contexts like your app's structure and user behavior. It then blocks malicious requests and allows legitimate ones to access your app.

Furthermore, open-appsec’s code has also been published on GitHub, and the effectiveness of its WAF has been successfully proven in numerous tests by third parties. Hence, try open-appsec in the Playground today.

Key Features of open-appsec WAF

  • Machine Learning-Based Threat Prevention

  • Anti-Bot

  • Infrastructure as Code (IaC)

  • API Discovery and Security

  • SaaS Security Management

  • Intrusion Prevention (uses Snort Engine 3.0)


Although there’s no fixed price for this WAF, it has three pricing plans, as given below:

  • Community Edition: It is free and offers ML-based WAF, API security, and an IPS engine.

  • Premium Edition: This offers a pay-as-you-go plan for every 1 million HTTP requests monitored and analyzed. It also offers anti-bot, API schema enforcement standard support, and other features.

  • Enterprise Edition: This includes an annual payment per 100 million HTTP requests, a gateway virtual machine, the option to block anonymizers and malicious IPs using ThreatCloud, 24/7 enterprise support, and many other unique features.

Pros and Cons


  • Open-source

  • Fast technical support

  • Uses machine learning algorithms to protect against known and unknown attacks

  • Very few false positives

  • Does not increase web latency

  • API discovery to manage your attack surface


  • Relatively new WAF

Cloudflare WAF by Cloudflare

Cloudflare WAF is a cloud-based WAF that protects your web applications from common vulnerabilities and attacks by providing services like bot protection, DDos protection, and limited machine learning capabilities for three attack types. It uses predefined and customized rulesets and signatures to protect your web app from OWASP Top 10 attacks and others.

Key Features of Cloudflare WAF

Ruleset and Signature-Based Web Application Security

  • Threat Analytics and Reporting

  • Virtual Patching

  • IP Blacklisting and Whitelisting


Cloudflare WAF has three pricing plans:

  • Pro: It is billed as $25/month and $240/yr. It comes with all the Basic Plan support plus additional support tickets.

  • Business: It is billed $250/month and $2,400/year. It offers all the Pro Plan support, chat support, and a 100% uptime Service-Level Agreement (SLA).

  • Enterprise: It is custom priced and billed annually. It offers 100% uptime SLA, secure credits, 24/7/365 tickets, phone service, and all the support in the Business Plan. This pricing option is best for agencies that manage multiple web apps.

Pros and Cons


  • Easy deployment and UI

  • Good at protecting against known attacks, malicious bots, and DDoS

  • Offers customizable rulesets to help you personalize your app’s security


  • Incorporating it with some hosting platforms can result in increased web latency

Imperva SecureSphere Web Application Firewall by Imperva, Inc.

Imperva/Incapsula WAF is a cloud-based and on-premises WAF that uses certain rules to protect your web app against common attacks like the OWASP Top 10 attacks, SQLi, XSS, etc.

Its cloud version offers application security services like the following:

  • DDoS Protection

  • Advanced Bot Mitigation

  • SIEM Integrations

  • CDN

Furthermore, its on-premises version offers all the above features plus customizable policy management rules that help you monitor and control the security of multiple sites simultaneously.

Its most distinctive feature is its Runtime Application Self-Protection (RASP). This feature detects and blocks attacks that originate inside your applications, like SQL injection, CSRF, and clickjacking. Some of its other features are listed below.

Key Features of Imperva WAF

  • API Security

  • Bot Protection

  • DDoS Protection

  • Runtime Protection


For pricing details, it is necessary to contact them for a price quotation.

Pros and Cons


  • Can be deployed both in the cloud and on-premises

  • Low false positives

  • Effective bot mitigation

  • Great technical support


  • Incomprehensive analytics and reporting section

  • No clear pricing plan

Barracuda Web Application Firewall by Barracuda Networks

Barracuda WAF comes with a varied feature set to keep your web application safe. This solution includes a set of policies, signatures, and rules to monitor, analyze, and block malicious attacks in incoming requests. Its access control engine allows you to create detailed access control policies and rules to authenticate benign traffic without modifying your application's architecture.

It dutifully decrypts all encoding formats in incoming traffic and applies all set policies and rules before allowing legitimate requests to access your app. Additionally, it inspects and encrypts web server responses to prevent exposing sensitive data in outgoing requests. Not only this, it caches and compresses this data to ensure fast delivery.

Key Features of Barracuda WAF

  • API Protection

  • Bot Attack Mitigation

  • Active Threat Intelligence

  • Reporting and Analytics

  • Application Load Balancing and Monitoring


Barracuda WAF offers a free trial but doesn't provide any pricing information on the website. They also offer questionnaires to help you choose the right deployment type and feature set for your application.

Pros and Cons


  • Easy installation

  • Comprehensive insights on attacks and app activity

  • Bot protection feature using a machine learning application in a security approach

  • Uses IP reputation and behavioral analysis to protect against DDoS attacks


  • Highly suitable for large businesses and enterprises

  • Unclear pricing plan

AWS Web Application Firewall by Amazon Web Services, Inc.

AWS WAF is a cloud and on-premises WAF that monitors web traffic requests and prevents attacks. It uses predefined and custom rules to filter out known web attacks and is capable of deploying third-party vendor rulesets from the AWS marketplace. It also allows you to determine the subsequent actions to be taken after a web request has been analyzed; this could be to grant access, block access, or present a customized page (usually a captcha).

Key Features of AWS WAF

  • Full-Feature API Administration

  • Integration with AWS Firewall Manager

  • Real-Time Account Visibility

  • Bot Protection and Control

  • Account Takeover Fraud Prevention


AWS WAF pricing isn't fixed. Instead, it's based on three factors which have been listed below:

  • The number of access control lists that you create

  • The number of rules configured

  • The number of web requests that your web app receives

  • The number of add-ons per web content list

Pros and Cons


  • Protects against known web attacks based on different available managed rulesets

  • Doesn't increase web latency

  • Easily integrated with other Amazon Web Services

  • Easy to deploy


  • Can only be used by AWS customers

Akamai Kona Site Defender byAkamai Technologies, Inc.

Akamai Kona Site Defender protects your web application from common attacks like SQLi, XSS, OWASP Top 10 attacks, etc. Its most outstanding aspect is the self-tuning feature that adapts to your web app’s structure to offer better protection. Also, it uses machine learning to analyze all security triggers and differentiate malicious attacks from legitimate attacks.

Key Features of Kona Site Defender

  • Self-Tuning Application Security

  • Advanced API Discovery and Protection

  • Kona Rules

  • Application and Network-Layer Control

  • Actionable Insights and Reporting


For pricing details, it is necessary to contact the Akamai sales team for a price quotation.

Pros and Cons

Self-Tuning Application Security

  • Advanced API Discovery and Protection

  • Kona Rules

  • Application and Network-Layer Control

  • Actionable Insights and Reporting


For pricing details, it is necessary to contact the Akamai sales team for a price quotation.

Pros and Cons


  • Fast Technical Support

  • Allows room for personalized web app security using its WAF rules

  • Effectively protects against application layer attacks

  • Allows you to monitor traffic from specific IP addresses, geographical locations, etc.


  • Some cases of increased web latency

  • Complex user interface

  • Some WAF rules are quite complex to configure

FortiWeb by Fortinet, Inc.

This multilayered WAF protects your web application from known and unknown attacks. When integrated with FortiGuard, it updates you on emerging vulnerabilities and offers a heuristic detection engine. Additionally, it offers services like load balancing, SSL offloading, etc., to help boost your app’s load time.

Key Features of FortiWeb

  • Vulnerability and Threat Scanning

  • Advanced Threat Protection (uses FortiSandbox)

  • DoS Protection

  • Prevents and Reverses Defacement

  • Multidimensional Visibility and Advanced Reporting


While FortiWeb offers a 15-day free trial, its cost varies based on your configuration choices. Additionally, you can spend $0.085 to $4.43 on instances per hour.

Pros and Cons


  • Easy and fast to deploy

  • Effectively blocks known and unknown attacks

  • Great technical support

  • Performs effective vulnerability scanning and geolocalization

  • Operates perfectly during peak traffic times


  • Incomprehensive analytics section

  • Complex documentation

Azure Web Application Firewall by Microsoft Corporation

Azure WAF is a cloud-native service that protects your web apps from common web-hacking techniques such as SQLi, XSS, etc. It can be deployed in minutes to give insights into your app’s environment.

In general, it is a cloud-based WAF that uses managed and custom rules, exclusion lists, and policies to ensure the safety of all your Azure-hosted WAFs.

Key Features of Azure WAF

  • Application Security Rules and Policies (Both Custom and Managed)

  • Comprehensive Protection Against OWASP Top 10 attacks

  • Real-Time Security Visibility and Alerts

  • Full REST API Support


There are no specific pricing plans for the WAF, as it is available bundled with the Azure Application Gateway, but they offer a pricing calculator to help you estimate costs.

Pros and Cons


  • Fast deployment

  • Simultaneously carries out identity validation and load balancing to help increase web app efficiency

  • Effectively protects multiple web apps simultaneously

  • User interface is easy to navigate


  • Exclusion list can be difficult to configure and manage

  • Some cases of false positives

Prophaze Web Application Firewall by Prophaze Technologies, Inc.

Prophaze WAF is best known for the security it offers to APIs deployed on Kubernetes clusters. This cloud and on-premises WAF use attack detection algorithms to monitor incoming and outgoing requests and employs the use of artificial intelligence to stop attacks and protect your web apps.

Furthermore, it protects and notifies you of real-time suspicious activities in your web app. It also uses custom rules (no predefined rules) to help you streamline your app's security. Without human intervention or configuration, it automatically identifies threats and implements appropriate security policies to protect your data.

Key Features of Prophaze WAF

  • Machine Learning-Based App Behavioral Detection

  • DDoS Protection

  • Virtual Patching

  • API Security


There are no fixed plans, and pricing depends on the following factors:

  • The number of URLs and APIs you’re using

  • Your web app's bandwidth consumption (for SaaS-hosted web apps)

  • The type of WAF deployment you choose

  • The nature of the technical support you’d like to receive

  • The billing method you choose – monthly, yearly, or pay-as-you-go

Pros and Cons


  • Fast and easy setup

  • Detailed descriptions of incoming and outgoing requests in the analytics dashboard


  • Some cases of false positives

F5 Advanced Web Application Firewall by F5 Networks, Inc.

F5 Advanced WAF is best known for the comprehensive and flexible web app security it provides without compromising a web app’s performance.

One of its most impressive features is its effective app-layer DOS protection. It uses machine learning to carry out reputation matching and to analyze the behavior of incoming traffic. Additionally, it offers proactive bot protection.

Key Features of F5 Advanced WAF

  • Geolocation-Based Request Blocking

  • App-Layer DoS Protection (uses Machine Learning and Behavioral Analysis)

  • Data Encryption (uses DataSafe)

  • API Protocol Security

  • Anti-Bot Mobile SDK


There's no fixed pricing, but they offer a free trial.

Pros and Cons


  • Great tech support

  • Effectively protects against critical web app attacks

  • Doesn’t increase web latency


  • Has a complex user interface

  • Several cases of false positives

  • Ineffective layer 3 and 4 protection

  • Unclear documentation and deployment guide

NGINX App Protect by NGINX, Inc., a subsidiary of F5 Networks, Inc.

NGINX App Protect is part of the replacement of F5's popular Application Security Manager (ASM). It is popular for its application security wrapper for DevOps environments and live websites. It is one of the few web application security solutions that block large requests to help conserve your CPU's time, memory, and disk space. Furthermore, in combination with NGINX Plus, it also acts as an API gateway, software load balancer, content cache, etc.

Key Features of NGINX App Protect

  • Seamless Integration with DevOps Environments

  • API Protection and Cookie Enforcement

  • Data Security (uses F5 Data Guard)

  • IP Address Blacklisting

  • Protection Against OWASP Top 10 attacks


There’s no fixed pricing, but they offer a free trial.

Pros and Cons


  • Easily integrated into all DevOps environments

  • Doesn’t increase web latency

  • Offers a free trial

  • Strong documentation

  • Functions as a capable reverse proxy


  • Takes time to set up.

AppTrana Web Application Firewall by Indusface

AppTrana WAF is popularly known for its combined web scanning, WAF, CDN, and DDoS protection services. It offers a slightly different web application security approach than other WAFs. Instead of waiting for web attacks to manifest, it scans web applications at intervals to discover vulnerabilities in your code, after which it alerts you or fixes it.

Furthermore, it offers an option to manually pen-test your web app, help you customize the rules that protect it, and manually help reevaluate your app's security to check for false positives.

Key Features of AppTrana WAF

  • Web Application Scanning

  • Bot Mitigation Capabilities.

  • DDoS Protection

  • API Security

  • WAF Custom Rules


It offers two pricing plans:

  • The advanced plan costs $99/month plus a 14-day free trial

  • The premium plan costs $399/month with no free trial

Pros and Cons


  • Effectively protects web applications against DDos, bot attacks, SQLi, OWASP Top 10 attacks, etc.

  • Affordable

  • Easy to set up

  • Great customer support


  • Only available for use in a few geographical locations

Citrix Web Application Firewall by Citrix Systems, Inc.

Citrix WAF protects your web app from data losses, security breaches, unauthorized web modifications, and other web attacks. It offers a WAF learning mode that offers policy recommendations by monitoring your application’s traffic and provides improved attack prevention.

Key Features of Citrix WAF

  • API Security (includes Rate Limiting, Threat Protection, etc.)

  • Bot Management and DoS Protection

  • SIEM Integrations and Detailed Analytics

  • Signature and Behavior-Based Web Application Protection

Pros and Cons


  • User interface is simple to navigate

  • Effectively protects against known and unknown web attacks

  • Can be accessed remotely across multiple devices


  • Sometimes experiences slow connection and loading time, especially when used with a VPN


With the proliferation of cyber attacks in recent years, organizations must deploy effective WAFs to safeguard their web assets. The WAFs discussed in this article represent some of the market's best options, each with its own strengths and weaknesses.

Remember that when choosing a WAF, it is important to consider its key features, pricing, and pros and cons. For instance, open-appsec WAF is a highly viable option. It is open-sourced and uses two machine learning algorithms to protect against known and unknown attacks effectively. It has a free version and two other paid versions and records near-zero cases of false positives. Try open-appsec in the Playground today.


Is WAF an API gateway?

No, a WAF is not an API gateway.

A WAF sits before web applications and analyzes all incoming traffic to detect, filter, and block malicious traffic. In contrast, an API gateway only protects the entry point for all API requests, allowing organizations to apply authentication, authorization, and throttling policies to incoming API traffic.

Meanwhile, open-appsec WAF can be integrated with a Kong API gateway to protect the API gateway, Web APIs, and Web Apps against known and unknown attacks.

Does Cisco have a WAF?

Cisco offers an advanced Web Application Firewall (WAF) as part of its security solutions portfolio. Cisco WAF uses adaptive security and machine learning to identify malicious requests and allow legitimate users access to your web app.

What is Next-Gen Firewall (NGFW) vs. Traditional WAF?

NGFWs, like open-appsec, contain most of the technologies in a traditional firewall in addition to machine learning-based web application security. It doesn’t use exception handling or rules. Hence, it preemptively protects web apps from known and unknown attacks. open-appsec extras like deep packet inspection and filtering, antivirus, etc.

Traditional WAFs, on the other hand, use exceptions, rules, and policies to web applications and APIs from attacks. This web application security approach works well for known attacks but cannot preemptively protect against new and emerging attacks.


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

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