导航|地址|刷新
Revalidation

Skip to contentDocumentation Index
Fetch the complete documentation index at: https://developers.cloudflare.com/cache/llms.txt
Use this file to discover all available pages before exploring further.

Docs Directory API SDKs Changelog

Search

Log in

Cache / CDN

/

Overview

Plans

Get started

Concepts

CDN-Cache-Control

Cloudflare cache responses

Customize cache

Default cache behavior

Head Requests and Set-Cookie Headers

Origin Cache Control

Retention vs Freshness (TTL)

Revalidation

Vary

Cache configuration

Purge cache

Overview

Purge by single-file

Purge everything

Purge cache by cache-tags

Purge cache by hostname

Purge cache by prefix (URL)

Purge cache key resources

Purge varied images

Purge zone versions via API

Cache Response Rules

Overview

Create a rule in the dashboard

Create a rule via API

Terraform example

Available settings

Cache Rules

Overview

Create a rule in the dashboard

Create a rule via API

Terraform example

Available settings

Order and priority

Examples

Overview

Browser Cache TTL

Bypass Cache on Cookie

Cache by Device Type

Cache Deception Armor

Cache everything for hostnames in a list

Cache Everything while ignoring query strings

Cache Level (Cache Everything)

Cache TTL by status code

Custom Cache Key

Edge Cache TTL

Origin Cache Control

Query String Sort

Respect Strong ETags

Migration from Page Rules

Edge and Browser Cache TTL

Overview

Set Browser Cache TTL

Always Online

Cache by status code

Cache keys

Caching levels

Tiered Cache

Advanced configuration

Serving tailored content

Cache Reserve

Crawler Hints

Early Hints

Query String Sort

Vary for images

Performance review

Cache Analytics

Cache performance

Cache security

Avoid web cache poisoning

Cache Deception Armor

Cross-Origin Resource Sharing (CORS)

Reference

CDN Reference Architecture ↗

CSAM Scanning Tool

Development Mode

Using ETag Headers with Cloudflare

Interaction with Cloudflare products

Customize cache behavior with Workers

How Workers interact with Cache Rules

Enable cache in an R2 bucket

Control cache access with WAF and Snippets

Troubleshooting

Dynamic content and login issues

Issues with MP4 videos on iOS and Safari

Bot Management cookie causes cache bypass in O2O setups

edgeResponseBytes and cacheResponseBytes discrepancy

Always Online

Changelog

Glossary

Agent resources

Agent setup ↗

Cloudflare Skills ↗

Code Mode MCP Server ↗

Domain-specific MCP Servers ↗MCP

Cache llms.txt ↗

Cache llms-full.txt ↗

Cloudflare Docs llms.txt ↗

Cloudflare Docs llms-full.txt ↗

Home

/Cache / CDN

/Concepts

/Revalidation

Revalidation

Last updated Jun 26, 2026|Copy as Markdown|View as Markdown|Agent setup

OverviewStale-while-revalidateAsynchronous revalidationControlling stale behavior Directives that disable stale-while-revalidateSmart revalidation towards users

Stale-while-revalidate

When a cached asset expires, Cloudflare uses the stale-while-revalidate directive in Cache-Control to determine whether it can continue serving the stale asset while fetching a fresh copy from the origin. If the directive is present and the asset is within the allowed staleness window, Cloudflare serves the expired content to visitors and revalidates in the background. By using headers like If-Modified-Since and ETag, Cloudflare validates content without fully re-fetching it, reducing origin traffic.

Asynchronous revalidation

Revalidation is fully asynchronous. When a cached asset expires and stale-while-revalidate is set, the first request that arrives after expiry triggers revalidation in the background. That request immediately receives stale content with an UPDATING status instead of blocking until the origin responds. All following requests also receive stale content with an UPDATING status until the origin responds. Once revalidation completes, subsequent requests receive fresh content with a HIT status.

If the stale content is still valid, Cloudflare sets a new TTL. If the content has changed, the origin provides fresh content to replace the old.

Controlling stale behavior

Cloudflare only serves stale content during revalidation if your origin includes the stale-while-revalidate directive in its Cache-Control header. Without this directive, visitors wait for the origin to respond before receiving content.

If your origin sets stale-while-revalidate but you want to override it, you can disable stale serving through the Serve stale content while revalidating setting in Cache Rules.

Directives that disable stale-while-revalidate

When Origin Cache Control is enabled, the following Cache-Control directives prevent Cloudflare from serving stale content, per RFC 9111 §4.2.4 ↗:

must-revalidate — Prohibits serving stale content; the cache must revalidate with the origin first.

proxy-revalidate — Same as must-revalidate, but only applies to shared caches (like Cloudflare).

s-maxage — Implies proxy-revalidate semantics, so shared caches cannot serve stale content.

no-cache — Requires revalidation before serving any cached response.

If any of these directives are present alongside stale-while-revalidate, Cloudflare will not serve stale content — requests will return EXPIRED instead of UPDATING.

Workaround for different edge and browser TTLs

If you need stale-while-revalidate behavior with a different TTL for Cloudflare than for browsers, do not use s-maxage. Instead, configure your origin to send max-age with stale-while-revalidate, then use Edge Cache TTL in Cache Rules to set a separate TTL for Cloudflare.

For all available directives or behavior when Origin Cache Control is disabled, refer to Cache-Control directives.

Smart revalidation towards users

When both Last-Modified ↗ and Etag ↗ headers are absent from the origin server response, Smart Edge Revalidation will use the time the object was cached on Cloudflare's global network as the Last-Modified header value. When a browser sends a revalidation request to Cloudflare using If-Modified-Since or If-None-Match, our global network can answer those revalidation questions using the Last-Modified header generated from Smart Edge Revalidation. In this way, our global network can ensure efficient revalidation even if the headers are not sent from the origin.

PreviousRetention vs Freshness (TTL)NextVary

Was this helpful?

YesNo

Edit pageReport issue

On this page

Overview

Stale-while-revalidate

Asynchronous revalidation

Controlling stale behavior

Directives that disable stale-while-revalidate

Smart revalidation towards users

Edit pageReport issue

Getting started
PlansContact salesPartnersFind a partnerStartupsUnder attack?Domain name search

Company
AboutCareersInvestorsPressPress kitGlobal network

Public interest
Project GalileoAthenian ProjectCloudflare for CampaignsProject FairshotImpact/ESG

Compliance
Compliance resourcesTrust HubData ProtectionResponsible AITransparency reportReport abuse

Resources
App innovation reportCloudflare RadarCase studiesStatusSupportEventsBlog

Developers
DocumentationLearning centerCommunity

Solutions
SSE and SASE platformCloudflare AI CloudAI SecurityFrontend Development PlatformMulti-Tenant Platform DevelopmentWeb Security Platform

Start BuildingLog In

© 2026 Cloudflare, Inc.

Privacy policy|Report security issues|Terms of use|Trademark
|
Your privacy choices

Docs

------
导航页打开网址