Amazon SNS
What is it?
Amazon SNS is AWS's managed pub/sub service that pushes messages from a topic to many subscribers at once, like other services, queues, or notifications.
Explain like I'm 5
Why was it created?
Teams needed an easy way to broadcast events to many recipients on AWS. SNS was created as managed publish/subscribe messaging.
Where is it used?
- Fan-out notifications
- Event broadcasting to services
- Triggering multiple queues
- Alerts (email, SMS, push)
Why should developers care?
SNS is the standard AWS way to fan out notifications and events, often paired with SQS, so cloud developers use it frequently.
How does it work?
Publishers send a message to an SNS topic, and SNS pushes a copy to every subscriber. Subscribers can be SQS queues, Lambda functions, HTTP endpoints, email, or SMS — enabling one-to-many delivery without polling.
Real-world example
An 'order placed' event is published to an SNS topic that fans out to three SQS queues — billing, shipping, and analytics — each processing it independently.
Common use cases
- One-to-many event fan-out
- Triggering multiple consumers
- System and user notifications
- SNS-to-SQS fan-out patterns
Advantages
- Push-based, no polling
- One message to many subscribers
- Many subscriber types
- Fully managed
Disadvantages
- Not durable storage like a queue
- AWS-specific
- Delivery semantics differ by subscriber
- Best paired with SQS for reliability
When should you use it?
When one event should be pushed to multiple subscribers at once.
When should you avoid it?
When you need a durable work queue for a single consumer — use SQS.
Alternatives
Related terms
Interview questions
Beginner
- What is Amazon SNS?
- What is pub/sub?
Intermediate
- How does SNS differ from SQS?
- What can subscribe to an SNS topic?
Senior
- Why combine SNS with SQS (fan-out)?
- How do you ensure reliable delivery with SNS?
Common misconceptions
- "SNS stores messages until consumed" — it pushes messages; for durable buffering, subscribe an SQS queue.
- "SNS and SQS are interchangeable" — SNS is push-based fan-out; SQS is a pull-based durable queue.
Fun facts
- SNS stands for Simple Notification Service.
- The 'SNS-to-SQS fan-out' pattern is a classic AWS messaging design.
Timeline
- 2010 — Amazon SNS launches
Learning resources
Quick summary
Amazon SNS is AWS's managed pub/sub that pushes a published message to many subscribers — queues, functions, endpoints, or notifications — at once.
Cheat sheet
- Managed pub/sub on AWS
- Push to many subscribers
- Pairs with SQS for fan-out
- Notifications + event broadcast