Learn SQS by playing with it.
Drop producers and consumers onto a canvas, send messages, crash workers, watch visibility timeouts tick down — and finally understand distributed queues.
Every SQS concept, made visual.
Visibility Timeout
Watch messages go invisible and reappear when workers crash.
Dead Letter Queues
Trace poison messages from retry loops into the DLQ.
FIFO + Message Groups
See ordering preserved per group, parallelism across groups.
Retries & Backoff
Tune maxReceiveCount and watch redrive policies kick in.
Long vs Short Polling
Compare empty receives, cost, and latency side by side.
Batching & Throughput
Send and receive in batches to push thousands of msg/s.
SNS Fan-out
One publish, N queues — model event-driven architectures.
Idempotency
Why at-least-once delivery forces idempotent consumers.
Step through the lifecycle of every single message.
Pause time, scrub the timeline, and inspect each message: ID, group, receive count, visibility deadline. Crash a worker mid-processing and watch the message reappear.
- Step-by-step executionTick forward one event at a time.
- Inject failuresCrash workers, drop messages, throttle consumers.
- Live metricsQueue depth, in-flight, age of oldest message.
- Editable paramsVisibility timeout, max receives, polling mode.
Break things on purpose.
Each lab puts you in front of a broken system. Diagnose duplicate deliveries, timeout mismatches, and infinite retry loops — then fix them.
A roadmap from zero to system design ready.
FAQ
Is this an actual AWS account simulator?+
No — SQS Lab models queue behavior locally in your browser to teach concepts. It mirrors AWS semantics closely but doesn't talk to real AWS.
Do I need to know SQS already?+
Not at all. Start at the concepts page and follow the roadmap. The simulator gives you intuition fast.
Can I use this to prep for interviews?+
Yes — the interview prep mode (coming) gives you broken systems to debug, just like a real system design round.
Stop reading about queues.
Start running them.
Open the simulator and have a working mental model of SQS within the next 10 minutes.