I would say the most prolific one is Kubernetes. Sure it has some parts broken out (controller manager, scheduler), but the main API server is a pretty big Go

I would say the most prolific one is Kubernetes. Sure it has some parts broken out (controller manager, scheduler), but the main API server is a pretty big Go monolith. At a far smaller scale, the SaaS product my company built, Domestica (https://about.domestica.app https://about.domestica.app), is a Go monolith. It has an integrated job/cron queue using PostgreSQL included as well, all within the same binary. This makes it easy for us to distribute it as a Docker image to our users who want a private instance (https://hub.docker.com/r/candiddev/domestica https://hub.docker.com/r/candiddev/domestica).