A pub/sub (publish-subscribe) messaging service for broadcasting messages to multiple subscribers.

ie. One producer, multiple subscribers

Key Features:

  • Push-based: Delivers messages to subscribers automatically.
  • Supports multiple targets: SQS queues, Lambda, HTTP endpoints, SMS, email.
  • Fan-out pattern: One message can go to many consumers.

Use Case:

  • Real-time alerts (e.g., “new signup”).
  • Fan-out to multiple systems (e.g., update cache, send email, trigger webhook).
  • Decouple microservices where one action should trigger many others.