Cloudflare Cache is a distributed content delivery network (CDN) that stores copies of your website's static and dynamic content in geographically distributed data centers. This edge computing approach reduces latency, decreases origin server load, and improves overall site performance.
Understanding how to configure and optimize Cloudflare Cache is essential for any serious web project that demands both speed and reliability. This guide covers the essential aspects including Cache Rules, TTL configuration, cache purging strategies, and Transform Rules that work together to deliver optimal caching performance at the edge. When properly configured, caching becomes a cornerstone of high-performance web development practices.
For static site hosting, Cloudflare Cache integrates seamlessly with Cloudflare Pages to provide automatic caching of deployed assets at the edge.
Understanding Cloudflare Cache Fundamentals
Cloudflare Cache operates at the edge, meaning content is stored in data centers distributed worldwide. Each cache entry has a time-to-live (TTL) that determines how long the content remains stored before being considered stale.
Request flow through Cloudflare's edge network with cache hit/miss decision points
How Cloudflare Cache Works
When a visitor requests content from a Cloudflare-protected website, the request passes through Cloudflare's global network before reaching your origin server. If the requested content is already cached at a nearby edge location, Cloudflare serves it directly without contacting your origin server.
The intelligent caching system automatically determines which content to cache based on file types, response headers, and caching rules. Static assets like images, CSS files, and JavaScript are typically cached automatically, while dynamic content requires explicit configuration.
Default Cache Behavior
By default, Cloudflare caches content based on several factors. Static resources with cacheable response codes (typically 200, 301, 302 status codes) and appropriate Cache-Control headers get cached automatically. The system considers the file extension, content type, and response headers to make caching decisions.
However, content with no-cache headers, set-cookie headers, or non-cacheable status codes is bypassed by default. Understanding these defaults helps you identify what works out of the box and what requires additional configuration through Cache Rules. This understanding is critical for SEO performance since page speed directly impacts search rankings.
Cache Rules: Precision Control Over Caching
Cache Rules provide granular control over what gets cached, how long it stays cached, and where in the network it's stored. Unlike the one-size-fits-all approach of older Page Rules, Cache Rules allow you to create sophisticated caching strategies based on URL patterns, file types, response headers, and other request characteristics.
Each Cache Rule consists of three key components
Matching Criteria
Define when to apply the rule using URL patterns, hostnames, file extensions, request methods, and headers
Actions
Specify what to do when matching requests are detected, such as caching or bypassing
Priority
Determine which rule takes precedence when multiple rules match the same request
Cache Level Settings
Cache Rules offer several cache level settings that determine caching aggressiveness:
Cache Everything - Forces caching of all content matching the rule, ignoring default caching logic. Works well for static assets but use carefully with dynamic content.
Bypass Cache - Prevents caching entirely for matching content. Essential for personalized pages, API endpoints, and authenticated routes.
Standard - Uses default Cloudflare caching behavior, respecting origin Cache-Control headers and other caching signals.
Origin Cache Control - Relies entirely on origin server Cache-Control headers for caching decisions, providing maximum control from your application.
Cache Eligibility Criteria
Cache Rules allow you to modify eligibility requirements. By default, Cloudflare only caches content with certain characteristics. Cache Rules can override these defaults, enabling caching of content that would otherwise be bypassed.
For example, configure rules to cache content with Set-Cookie headers (normally a caching blocker) or to cache responses with non-200 status codes.
TTL Configuration: Managing Cache Lifetime
TTL (Time To Live) is the cornerstone of cache management. It controls how long cached content remains valid before needing revalidation.
Edge Cache TTL determines how long Cloudflare's edge servers retain cached content. This setting directly impacts your origin server load and content freshness.
When setting Edge Cache TTL, consider how frequently your content changes. Static assets like logos, images, and bundled JavaScript might use TTLs measured in days or weeks. More dynamic content might use hours or minutes.
The maximum Edge Cache TTL varies by plan, with Pro and Business plans offering longer durations. TTL values can be set in seconds, minutes, or hours.
Cache lifecycle showing how content progresses from fresh to stale and through revalidation
Cache Purging Strategies
Cache purging removes cached content so that the next request fetches a fresh version from the origin. Effective purging strategies are essential for maintaining content freshness without waiting for TTL expiration.
| Method | Use Case | Precision |
|---|---|---|
| Single File Purge | Update individual pages or assets after content changes | High - specific URLs |
| Purge Everything | Major site changes, migrations, or complete refresh | Low - all cached content |
| Purge by Tag | CMS-managed sites where updates affect multiple pages | Medium - grouped content |
| Purge by Host | Clear cache for specific subdomains or domains | Medium - hostname-based |
Implementing Effective Purge Workflows
Automating cache purging improves both developer experience and content freshness:
Content Management Integration - When publishing new posts or updating pages, trigger automatic purges for affected URLs. Many CMS platforms have plugins or hooks that support this automation.
Deployment Pipeline Integration - When deploying new versions of static assets, purge old URLs or use cache-busting techniques like versioned filenames.
Redundant Purging - For critical updates, consider multiple purge methods together. Purge by URL for specific pages and by tag for associated content categories.
API-Based Purging
Cloudflare's API provides programmatic access to purge functionality. The purge endpoints accept lists of URLs, tags, or hostnames and execute purges asynchronously. For advanced automation, you can integrate purging with Cloudflare Workers for custom purge logic triggered by specific events.
API purging is rate-limited, so plan bulk purge operations carefully. For large-scale purges, consider batching requests and monitoring rate limits.
{
"files": [
"/page/about/",
"/blog/new-post/",
"/assets/main.css"
]
}
Transform Rules for Cache Optimization
Transform Rules modify HTTP requests and responses at the edge, enabling URL rewrites, header modifications, and other transformations that enhance caching effectiveness.
URL Rewrites
Normalize URLs, remove tracking parameters, and add version paths to consolidate cache variants and improve hit rates.
Header Modifications
Add, remove, or modify HTTP headers to control cache behavior and enhance security at the edge. Works with [Cloudflare SSL/TLS](/resources/guides/platform-docs/cloudflare/cloudflare-ssl/) for complete security.
Managed Transforms
Pre-configured transformations that automatically strip query parameters and normalize request paths.
Cache Integration
Transform Rules run before caching decisions, making them powerful tools for cache optimization.
Transform Rules processing flow showing where URL rewrites and header modifications occur in the request pipeline
Migration from Page Rules
Page Rules have been deprecated in favor of the unified Ruleset engine that includes Cache Rules, Transform Rules, and other rule types.
| Page Rules Setting | Cache Rules Equivalent |
|---|---|
| Cache Everything | Cache Level action with 'Cache Everything' |
| Bypass Cache | Cache Level action with 'Bypass Cache' |
| Edge Cache TTL | Edge Cache TTL action setting |
| Browser Cache TTL | Browser Cache TTL action setting |
| Disable Performance | Disabled via settings |
| Always Online | Separate Always Online toggle |
Migration Process
Migrating Page Rules involves recreating each rule's logic using Cache Rules expressions and actions:
- Inventory Existing Rules - Document all active Page Rules and their configurations
- Create Expressions - Convert rule matching criteria into expression syntax
- Configure Actions - Map settings to appropriate Cache Rules actions
- Test Thoroughly - Verify behavior matches original rules before deactivating Page Rules
- Activate and Monitor - Enable Cache Rules and monitor cache hit rates
Cloudflare provides automated migration assistance in the dashboard that analyzes existing Page Rules and suggests Cache Rules configurations.
Best Practices and Common Patterns
Static Asset Caching
For static assets, aggressive caching maximizes performance benefits:
- Set Edge Cache TTL to maximum allowed (varies by plan)
- Configure Browser Cache TTL for extended local caching
- Use cache-busting through versioned filenames rather than short TTLs
- Enable compression through Polish and Mirage features
- Consider Argo Smart Routing for optimized delivery paths
These caching strategies are essential components of modern web development workflows that prioritize performance.
Dynamic Content Strategies
Dynamic content requires balancing freshness against performance:
- Bypass cache for personalized or authenticated routes
- Use short TTLs with purging for frequently updated content
- Implement edge-side includes (ESI) for page composition
- Consider Cloudflare Workers for dynamic content processing
- Use vary headers to cache appropriate variations
For comprehensive traffic management, combine caching strategies with Cloudflare DNS to ensure reliable resolution and fast delivery.
When caching data from Cloudflare R2 storage or Cloudflare D1 databases, implement appropriate cache key strategies to avoid serving stale data.
Security Integration
Cache configuration should work alongside Cloudflare WAF to protect cached content from threats. WAF rules can be configured to allow legitimate traffic while blocking malicious requests before they reach cached resources.
Key security considerations:
- WAF operates before cache lookup, protecting your cached content from attacks
- Configure security headers through Transform Rules to enhance cached content protection
- Use rate limiting rules to prevent cache poisoning attempts
- Monitor security events to identify patterns that may indicate cache abuse
Performance Monitoring
Effective cache management requires monitoring key metrics:
| Metric | Indicates | Target |
|---|---|---|
| Cache hit ratio | Overall caching effectiveness | Above 80% |
| Origin response times | When caching isn't working | Low and consistent |
| Bandwidth savings | CDN value delivery | Significant reduction |
| Cache purge frequency | Content update patterns | Matched to content changes |
Use Cloudflare Analytics to track these metrics and identify optimization opportunities. Strong caching performance directly contributes to improved SEO rankings through faster page load times.