What makes an API idempotent?
PICTURE THIS: HOW TO EXPLAIN IT
Simple meaning
Repeating the same request leaves the same server state.
WHY — APIs instead of guessing?
Why interviewers care about APIs:
who only read docs from people who shipped.
and tied to Backend work.
Name the idea, why it exists, then one short example.
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1Repeating the same request
leaves the same server state.
- 2GET, PUT, and DELETE
are typically idempotent
- 3How it works
POST create usually is not.
- 4Idempotency keys help payment
APIs survive client retries safely.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
Repeating the same request leaves the same server state. GET, PUT, and DELETE are typically idempotent