At its re:Invent user conference in Las Vegas today, public cloud infrastructure provider Amazon Web Services (AWS) said that it has turned on distributed denial of service (DDoS) attack mitigation technology, called AWS Shield Standard, for all of its customers, free of charge.

It “protects you from 96 percent of the most common attacks today, including SYN/ACK floods, Reflection attacks, and HTTP slow reads,” AWS chief evangelist Jeff Barr wrote in a blog post.

To help customers prevent more sophisticated attacks, AWS is also introducing a premium tier called AWS Shield Advanced. It lets customers call in a special support team that’s available 24 hours a day, 7 days a week. Customers can get notifications when certain infrastructure is used to stop attacks.

When AWS detects attacks, “we will work together with DDoS protection teams to create the right level of protection using WAF [web application firewall]. We will also keep an eye on cost, making sure you don’t incur any additional cost by using our service,” Amazon vice president and chief technology officer Werner Vogels said.

The launch of this service comes three years after Google introduced the Project Shield DDoS mitigation tool, but only some organizations have been able to use that tool, and Google hasn’t made it available for anyone to use in its Google Cloud Platform.

The launch of AWS Shield Standard and AWS Shield Advanced is an example of how AWS, the biggest public cloud today, is able to come out regularly with new services while its competitors strive to catch up. Meanwhile, AWS and the others also compete on price, variety of infrastructure, and geographic availability. Microsoft Azure has not revealed a DDoS mitigation tool.