Glossary term
What is Idempotency? Meaning for developers
In System Design
Doing something twice has the same effect as doing it once. Example: A lift button: pressing it 5 times still calls one lift. Retrying a payment with the same key charges once.
Learn it properly · System DesignLesson 34: Idempotency, Pagination & API VersioningA retried payment that charges twice, a list endpoint that loads three million rows, a renamed field that crashes every old app. Idempotency keys, cursor pagination and careful versioning — the unglamorous details that separate a demo API from a production one.In API Design
Doing the same request once or many times leaves the server in the same state, so a retry is safe.
Learn it properly · API DesignLesson 1: HTTP Methods, Status Codes and Idempotency in PracticeGET, POST, PUT, PATCH and DELETE used correctly, the status codes that matter, and why idempotency decides whether a retry is safe.