[kronin]

Istio comes with its own ingress controller that uses envoy. This is an alternative to ambassador, as already said, or nginx-ingress.

[infinitebyte]

Ambassador is positioned as API GW instead of ingress controller. Contour is designed to be an ingress controller. API GW also acts as ingress controller but has more features than ingress controller to manage the APIs. Contour is comparable to Istio-ingress, nginx ingress controller or HAProxy ingress controller.