BackendHigh signal
Idempotency
Also written as Idempotent
A property of an operation where running it multiple times has the same effect as running it once — important for safely retrying requests (like a payment) without accidentally duplicating the result.
Think of it like
Like a light switch — flipping it 'on' five times in a row still just leaves the light on once, not five times brighter.
Junior or senior?
Junior sounds like
Hasn't considered what happens if a request gets retried.
Senior sounds like
Can point to a specific endpoint — often payments — they deliberately made idempotent, and how.
Ask them
“Tell me about an endpoint you made idempotent, and why that mattered for that specific use case.”