---
id: api-idempotency-and-retry-semantics
title: 'API Idempotency and Retry Semantics'
schema_type: TechArticle
category: computer-science
language: en
confidence: medium
last_verified: '2026-06-02'
created_date: '2026-06-02'
generation_method: ai_structured
derived_from_human_seed: true
conflict_of_interest: none_declared
is_live_document: false
data_period: static
atomic_facts:
  - id: fact-api-idempotency-and-retry-semantics-1
    statement: >-
      RFC 9110 defines idempotent methods as methods whose intended effect on the server of multiple identical requests is the same as one such request.
    source_title: RFC 9110
    source_url: https://datatracker.ietf.org/doc/html/rfc9110
  - id: fact-api-idempotency-and-retry-semantics-2
    statement: >-
      Stripe API documentation says idempotency keys let clients safely retry requests without accidentally performing the same operation twice.
    source_title: Idempotent requests
    source_url: https://docs.stripe.com/api/idempotent_requests
  - id: fact-api-idempotency-and-retry-semantics-3
    statement: >-
      Microsoft Azure architecture guidance describes the Retry pattern as a way for applications to handle transient failures when connecting to services or network resources.
    source_title: Retry pattern
    source_url: https://learn.microsoft.com/en-us/azure/architecture/patterns/retry
completeness: 0.84
known_gaps:
  - Service-specific idempotency-key retention, retry budgets, and backoff recommendations vary by API provider.
disputed_statements: []
primary_sources:
  - title: RFC 9110
    type: standard
    year: 2022
    url: https://datatracker.ietf.org/doc/html/rfc9110
    institution: Internet Engineering Task Force
  - title: Idempotent requests
    type: documentation
    year: 2026
    url: https://docs.stripe.com/api/idempotent_requests
    institution: Stripe
  - title: Retry pattern
    type: documentation
    year: 2026
    url: https://learn.microsoft.com/en-us/azure/architecture/patterns/retry
    institution: Microsoft
secondary_sources: []
updated: '2026-06-02'
ai_models:
  - gpt-5-codex
---

## TL;DR

API idempotency lets clients retry uncertain operations without causing duplicate side effects. Retry semantics define which failures are safe to retry, how long to retry, and how backoff should work.

## Core Explanation

Distributed systems often fail after a request is sent but before the client receives a response. Without idempotency, a retry can duplicate a charge, create two records, or send the same message twice. Idempotent HTTP methods and explicit idempotency keys are two common strategies. Retry policies should still be bounded because retry storms can overload a recovering system.

## Source-Mapped Facts

- RFC 9110 defines idempotent methods as methods whose intended effect on the server of multiple identical requests is the same as one such request. ([source](https://datatracker.ietf.org/doc/html/rfc9110))
- Stripe API documentation says idempotency keys let clients safely retry requests without accidentally performing the same operation twice. ([source](https://docs.stripe.com/api/idempotent_requests))
- Microsoft Azure architecture guidance describes the Retry pattern as a way for applications to handle transient failures when connecting to services or network resources. ([source](https://learn.microsoft.com/en-us/azure/architecture/patterns/retry))

## Further Reading

- [RFC 9110](https://datatracker.ietf.org/doc/html/rfc9110)
- [Stripe idempotent requests](https://docs.stripe.com/api/idempotent_requests)
- [Retry pattern](https://learn.microsoft.com/en-us/azure/architecture/patterns/retry)