Amazon.com runs on EKS (and other services). You can see public customer references here https://aws.amazon.com/eks/customers/ https://aws.amazon.com/eks/custom

Amazon.com runs on EKS (and other services). You can see public customer references here https://aws.amazon.com/eks/customers/ https://aws.amazon.com/eks/customers/ ECS is 3 years older than EKS (2015 vs 2018) and a lot of AWS services launched (or planned to launch) during that time which is a very valid reason lots of customers picked ECS. (I work on the EKS team)