Versioned ClientLibs

Available since version 1.2.0


Allow CSS and JavaScript served via AEM ClientLibs to be cached client-side with long TTLs.

How to Use

Add a Sling rewriter configuration node (example below) that includes the versioned-clientlibs transformer type to you project.

The URIs to clientlibs will be rewritten in the format /path/to/clientlib.md5hash.js

Prior to version 1.5, the last modified timestamp was used instead of a hash.


This re-writer does NOT support

  • URIs embedded in CSS or JavaScript, including: background-images, web fonts, etc.
  • Relative URIs, e.g. etc/clientlibs/mysite/styles.css
  • URIs including a scheme, e.g. and //
  • URIs to non-AEM HtmlClientLibrary resources, e.g. /etc/designs/mysite.css
  • Tags contained in conditional comments.
  • ClientLibs included by Javascript (e.g. when leveraging the property channels)

Rewriter Configuration Node

The easiest way to configure the rewriter pipline is just to copy /libs/cq/config/rewriter/default to a path inside your application, e.g. /apps/myapp/config/rewriter/versioned-clientlibs. Note that the configuration node must be inside a four-level path that ends in config/rewriter.

To validate that your configuration was successful, look at the Sling Rewriter tab in the OSGi Web Console.

<?xml version="1.0" encoding="UTF-8"?>
<jcr:root xmlns:sling="" xmlns:jcr=""

Other transformers may or may not be necessary. Please refer to the default configuration at /libs/cq/config/rewriter/default to see the default set of transformers.

Apache Configuration

To configure Apache to send the right header to set a long TTL:

SetEnvIf Request_URI "(\.min)?\.[a-f0-9]+\.js" long_expires=true
SetEnvIf Request_URI "(\.min)?\.[a-f0-9]+\.css" long_expires=true
Header set Cache-Control max-age=2592000 env=long_expires

MD5 Enforcement (Since 2.11.0/3.8.0)

Optionally, a filter can registered which checks incoming requests for client libraries and ensures that the hash in the path is the correct value. To enable this, set the property enforce.md5 to true on the PID com.adobe.acs.commons.rewriter.impl.VersionedClientlibsTransformerFactory

transformer factory configuration

If you enable this option, the hash will be prefixed with ACSHASH to ensure that only rewritten paths are validated. Be sure to incorporate this into any web server or CDN rules.

Please report any issues with the Feature or documentation on the ACS AEM Commons GitHub Issue tracker.