"The Azure Event Grid takes events generated from Azure services, or custom apps, and routes them to chosen handlers. This service offers developers and operators a single event stream to tap into for serverless apps, app integration, or ops automation.
Microsoft claims that the Azure Event Grid scales to millions of events per second. The first 100,000 operations per month are free, and users pay $0.60 per million operations after that.
...services like Google Cloud Storage emit events to Google Cloud Pub/Sub, but this is only for a subset of services, and messaging topics are self-managed. In the AWS cloud, SQS takes events from a handful of services, and CloudWatch publishes events to a few types of handlers."