nginx - A high performance free open source web server powering busiest sites on the Internet.
Barracuda Web Application Firewall - Barracuda Web Application Firewall offers security and DDoS protection against automated & targeted attacks.
AWS WAF - AWS WAF is a web application firewall that helps protect your web applications from common web exploits.
Imperva Cloud Application Security - Deploy your applications and data where you want. When you want. Imperva keeps them secure in the cloud, on premises, and in hybrid clouds.
Cloudflare WAF - Whether you want automatic WAF protection from known vulnerabilities or have custom WAF rules, our real-time platform can do it.
Sucuri - Website Protection, Malware Removal, and Blacklist Prevention