Use Amazon SQS when you need a queue: messages wait safely until a worker polls for them, so senders and receivers never have to be online at the same time. Use Amazon SNS when one message needs to reach many subscribers at once: it pushes to apps, Lambda functions, SQS queues, phones by SMS or push, and email. The two also work together: SNS can fan a message out to several SQS queues.
I read AWS's product pages, FAQs and plans pages for both services. AWS's own FAQs answer the comparison directly, so I've leaned on their wording.
SQS and SNS side by side
| Amazon SQS | Amazon SNS | |
|---|---|---|
| Model | Message queue: consumers poll | Publish-subscribe: SNS pushes to subscribers |
| Receivers | Consumers read messages from the queue | Many subscribers per topic |
| Delivery | Standard: at least once; FIFO: exactly-once processing | Push with delivery retries; FIFO topics for strict order |
| Ordering | Standard is best effort; FIFO keeps exact order | FIFO topics keep strict order |
| Reaches people? | No, app to app | Yes: SMS, mobile push and email |
| Free option (as of October 2026) | Free tier: 1 million requests a month | Free tier: 1 million requests, 1 million mobile push and 1,000 email notifications a month |
Pull vs push, in AWS's words
Both FAQs carry the same answer. Amazon SNS lets applications send time-critical messages to multiple subscribers through a push mechanism, so nobody has to keep checking, or polling, for updates. Amazon SQS is a message queue that distributed applications use to exchange messages through a polling model, and it decouples the sending and receiving components so one can keep working when the other is busy or down.
That one difference shapes everything else. A queue holds work until something is ready to process it, which is why SQS suits background jobs, order processing and smoothing out traffic spikes. A topic broadcasts the moment something happens, which is why SNS suits alerts, notifications and triggering several systems from one event.
Delivery guarantees and ordering
SQS offers two queue types. AWS says standard queues provide at-least-once delivery, so a message can occasionally arrive more than once, and they try to preserve order but can't guarantee it because they're built to scale massively. FIFO queues preserve the exact order messages are sent and received and provide exactly-once processing. SQS also supports dead-letter queues for messages that keep failing.
SNS has standard and FIFO topics too. Its product page lists message filtering, batching, ordering and deduplication, plus archiving, replay, delivery retries and dead-letter queues for durability. It can also capture and fan out events from over 60 AWS services.
Using SNS and SQS together
You'll often see the two together. AWS's own getting-started tutorial for SNS is called Send Fanout Notifications, and the SNS plans page lists deliveries to SQS queues. In practice, one event, say a new order, is published to an SNS topic, and separate SQS queues for billing, shipping and email each get their own copy to work through at their own pace.
SNS can also reach people directly. Its application-to-person features send SMS texts, mobile push notifications and email, which SQS doesn't do. AWS says there's no charge for SNS deliveries to Lambda functions, though standard Lambda charges still apply.
Five questions to pick
- Does work need to wait until a worker is free? Use an SQS queue.
- Does one event need to reach several systems at once? Publish it to an SNS topic.
- Must messages be processed in exact order without duplicates? Use SQS FIFO queues or SNS FIFO topics.
- Do you need to text or email customers? SNS handles SMS, push and email.
- Want each downstream service to process a shared event independently? Fan out from SNS to one SQS queue per service.
If you're building apps that rely on notifications, my guide to outsourcing mobile app development covers the wider build, and this piece on modernising legacy systems explains why decoupling matters.
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My advice on SQS or SNS
Don't think of them as rivals: SQS is your to-do list and SNS is your loudspeaker. If you only need to hand work from one part of your app to another reliably, start with SQS; its free tier of 1 million requests a month covers plenty of small apps. If an event needs to trigger several things or reach people by text or email, add SNS, and fan out to SQS queues wherever the receiving work can't afford to lose a message.
Do you make cloud or developer tools? Tool makers can ask to be considered for a featured place in comparisons like this one.
Frequently asked questions
What's the main difference between SQS and SNS?
AWS says SNS sends messages to multiple subscribers through a push mechanism, while SQS is a message queue that applications read through a polling model.
Can SNS send messages to SQS?
Yes. The SNS plans page lists deliveries to SQS queues, and AWS's SNS tutorial on fanout notifications covers publishing one message to several subscribers.
Does SQS guarantee message order?
FIFO queues preserve the exact order messages are sent and received. Standard queues try to preserve order but don't guarantee it.
Is there a free tier for SQS and SNS?
Yes. AWS lists 1 million SQS requests a month free, and for SNS the first 1 million requests, 1 million mobile push notifications and 1,000 email notifications a month.
Can SNS send SMS and email?
Yes. SNS application-to-person messaging covers SMS texts, mobile push notifications and email.
