SNS vs Event Grid vs Pub/Sub — Event Messaging Compared
Compare AWS SNS, Azure Event Grid, and Google Cloud Pub/Sub for event-driven architectures. Pricing, patterns, and scale.
Feature Comparison
| Feature | Amazon SNS | Azure Event Grid | Google Cloud Pub/Sub |
|---|---|---|---|
| Global by default | No (regional) | No (regional) | Yes |
| Exactly-once delivery | FIFO topics only | At-least-once | Supported |
| Message replay | Limited | No | Yes (seek to timestamp) |
| Cost-optimized tier | No | No | Pub/Sub Lite |
Service Details
Amazon SNS
Fully managed pub/sub messaging for both A2A (application-to-application) and A2P (application-to-person) communication.
- A2A and A2P in one service
- FIFO topics for ordered delivery
- SMS/email/push notification support
- Message filtering at the subscription level
- Not ideal for high-throughput streaming
- Limited replay capability
- 256KB message size limit
Azure Event Grid
Event routing service designed for event-driven architectures. Routes events from Azure services and custom sources to handlers.
- Deep Azure service integration
- Event schema validation
- Dead lettering built-in
- CloudEvents support
- Not a traditional pub/sub
- Complex pricing model
- Azure-centric design
Google Cloud Pub/Sub
Global-scale messaging and event ingestion. Supports both streaming and batch, with Pub/Sub Lite for cost-optimized high-throughput.
- Global by default (no regional setup)
- Exactly-once delivery support
- Pub/Sub Lite for cost-optimized throughput
- Deep Dataflow integration
- More expensive at low volumes than SNS
- Per-byte pricing can surprise with large messages
- Ordering requires explicit configuration
When to Use Which
Choose SNS for simple fan-out pub/sub with notification channels (SMS, email). Choose Event Grid for Azure-native event routing. Choose Pub/Sub for global-scale messaging with replay and exactly-once delivery.
Event-driven architectures can generate surprising messaging costs at scale. CloudExpat helps monitor throughput, identify unused topics/subscriptions, and optimize batch sizes.
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