Meaning
Describing an operation that produces the exact same result no matter how many times it is repeated with the same parameters.
Three examples from work
Payment design
LeadOur payment charge endpoint must be strictly idempotent.
DevWe accept an Idempotency-Key header to prevent duplicate charges if the client retries.
Webhook reliability
DevExternal webhooks can be delivered multiple times during network retries.
ArchitectDesign your webhook consumer to be idempotent by checking message IDs before processing.
Database seeding
DevIs the database migration script idempotent?
DBAYes, it uses 'IF NOT EXISTS' clauses so running it multiple times is completely safe.
Pronounce 'eye-dem-POH-tent'. Critical in distributed systems and payment APIs to ensure network retries do not trigger duplicate effects.