Event Bridge VS SNS

EventBridge and SNS overlap enough that the choice is a genuine one. Both take a message from a publisher and push it to something else; both retry, both support dead-letter queues, both work across accounts and Regions. The differences that matter are narrower than they used to be, because SNS has since gained several of the capabilities that once made EventBridge the obvious answer.

The side-by-side comparison of both services, along with SQS and Kinesis, is on the section index.

What actually separates them

Routing versus broadcasting. EventBridge decides where an event goes: one bus, many rules, each with its own pattern and its own targets. SNS broadcasts: every subscriber to a topic receives the same message, subject to its own filter policy. If the destination depends on the content of the message, EventBridge expresses that directly; with SNS it becomes a topic-per-destination design.

Filtering. Both filter. SNS filter policies match on message attributes by default, and on the message body when the subscription sets FilterPolicyScope to MessageBody — so payload-based filtering is no longer a reason to reach for EventBridge. EventBridge patterns are richer (prefix and suffix matching, numeric and IP ranges, negation, exists) and are evaluated once per rule rather than once per subscription.

Scale of fan-out. SNS is built for very large subscriber counts: 12.5 million subscriptions per standard topic. An EventBridge rule takes five targets, a hard limit; larger fan-out means more rules, or an SNS topic as one of the targets.

Sources. EventBridge receives events from AWS services and SaaS partners without any publishing code, and can run rules on a schedule. SNS only carries what a publisher sends it.

Transformation. EventBridge can reshape an event per target with an input transformer, and enrich it with EventBridge Pipes. SNS delivers the message as published, raw or wrapped in its envelope.

Archive and replay. EventBridge archives events from a bus and replays them to it. SNS supports archive and replay on FIFO topics through an archive policy and a replay policy; standard topics have no equivalent.

Latency and cost. SNS is the lower-latency, lower-overhead path — it does less per message. EventBridge is priced per event published, SNS per API request and data transferred.

Use EventBridge when

• The destination depends on the content of the event
• The system must react to AWS service events, or to SaaS provider events, without a publisher being written for them
• Work has to be scheduled (cron or rate expressions)
• The event should be transformed or enriched before it reaches its target
• Archive and replay are needed on ordinary, non-FIFO traffic
• Accounts are being integrated through a shared bus

Use SNS when

• The pattern is straightforward pub/sub — the same message to every interested party
• Fan-out is wide, or the subscriber count is unbounded
• The destinations include endpoint types EventBridge does not deliver to directly: email, SMS and mobile push
• Latency matters more than routing sophistication
• Strict ordering and deduplication are required, which FIFO topics provide

They also compose. An EventBridge rule can target an SNS topic, which is the usual way to combine content-based routing with wide fan-out, and SNS can deliver into SQS queues so that each consumer gets its own buffered, retryable copy.