Where do the app updates come from/through, the carrier or Google?

I suspect that The OS and firmware updates comes from the carrier but I am not sure if the same is true for app updates. I am asking because Cricket is my carrier but I want a phone that they do not sell. I know that it's going to be a hassle getting any OS and firmware updates but that happens rarely but app updates seems to come everyday. I use financial apps that I want all updates early.

Welcome to Android Central! Apps are updated by the app developers, not Google or the carrier. They are updated through the app store where you got the app--so if you installed it from Google Play Store or Amazon Appstore, that's where the update comes from.