Cache Header Checker
Ensure your static assets are cached effectively to reduce server load.
Cache Header Checker
Analyze HTTP caching headers (Cache-Control, ETag, Expires) to see how a resource is cached by browsers and CDNs.
Enter an asset URL above to evaluate its browser caching configuration.
HTTP Caching Basics
Web performance relies heavily on caching. When a browser downloads a resource (like an image, CSS file, or script), it checks HTTP headers to determine if and how long it can keep a copy locally. Proper caching prevents unnecessary network requests, speeding up subsequent page loads.
Key Cache Headers
- Cache-Control: The primary header for caching directives. Common values include
max-age=...(cache for X seconds),no-cache(revalidate before using), andno-store(never cache). - ETag: An identifier for a specific version of a resource. The browser sends this back to the server to check if the file has changed (304 Not Modified).
- Last-Modified: A fallback or alternative to ETag, indicating when the file was last updated on the server.
- Expires: An older caching header that specifies an absolute date when the resource expires.
Cache-Control max-agetakes precedence over this.
Related Guides
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