Client Libraries (ClientLibs)

🔍 What Is It?

AEM Client Libraries are repository folders of type cq:ClientLibraryFolder that package CSS and JavaScript into named categories. Teams include those categories in templates or components so AEM can deliver the right files through /etc.clientlibs.

If someone asks "what are clientlibs in AEM," the practical answer is simple: clientlibs are AEM's asset delivery system for frontend code, handling categories, dependencies, bundling, minification, and cache-aware URLs.

Quick Facts

• →Used in: Site CSS, JavaScript, authoring-only assets, component assets, and frontend delivery through Dispatcher
• →Best for: Managing CSS and JS in reusable AEM projects without manual script ordering
• →Interview importance: High because clientlibs are a core AEM implementation topic
• →Production relevance: High because clientlib setup affects caching, performance, and publish delivery
• →Related topics: Components, HTL, editable templates, Dispatcher
• →Last updated: July 2026

What a clientlib contains

• →CSS files listed in css.txt
• →JavaScript files listed in js.txt
• →A categories property used for inclusion
• →Optional dependencies and embed properties for load ordering and bundling

Why teams use clientlibs

• →Bundles multiple CSS and JS files into predictable delivery groups
• →Helps manage dependency order between shared frontend assets
• →Supports minified production output
• →Works cleanly with cache-busting through generated clientlib URLs

🎯 Why Do We Need It?

Without clientlibs, AEM projects end up manually managing CSS and JavaScript includes, inconsistent load order, and fragile cache behavior across templates and components.

Clientlibs give teams a standard AEM-native way to organize frontend assets so Author, Publish, Dispatcher, and Cloud Service delivery stay easier to reason about.

Interview Relevance

• →Interviewers ask clientlibs to check whether you understand AEM frontend delivery beyond HTL markup alone
• →Strong answers explain categories, dependencies, embed, allowProxy, and why /etc.clientlibs matters on Publish
• →Senior discussions often move into caching, author-only assets, and debugging missing CSS or JavaScript in production

🏗️ What Happens in Real Projects?

Production Usage

In real AEM projects, clientlibs are used to separate base site assets, component-specific styles, vendor bundles, and author-only functionality. Teams usually include shared categories at the page level and smaller categories only where a component or template actually needs them.

A common setup includes:

• →mysite.base for typography, layout, and shared utilities
• →mysite.components for reusable component styling
• →mysite.author for editor-only enhancements
• →mysite.vendor for approved third-party libraries

Component-scoped clientlibs are also used when a feature should load only with a specific component or experience.

⚙️ How It Works

ClientLib Structure:

/apps/mysite/clientlibs/
  base/                          [cq:ClientLibraryFolder]
    categories: [mysite.base]
    dependencies: [cq.jquery]
    css.txt                      <- Lists CSS files
    js.txt                       <- Lists JS files
    css/
      main.css
      typography.css
    js/
      app.js
      utils.js

Including in HTL:

<sly data-sly-use.clientlib="/libs/granite/sightly/templates/clientlib.html">
<sly data-sly-call="${clientlib.css @ categories='mysite.base'}"/>
<!-- page content -->
<sly data-sly-call="${clientlib.js @ categories='mysite.base'}"/>
</sly>

Generated Output:

<link rel="stylesheet" href="/etc.clientlibs/mysite/clientlibs/base.min.css?...hash...">
<script src="/etc.clientlibs/mysite/clientlibs/base.min.js?...hash..."></script>

💻 Example

Creating a Client Library — Complete ClientLib setup for a component.

<?xml version="1.0" encoding="UTF-8"?>
<jcr:root xmlns:cq="http://www.day.com/jcr/cq/1.0"
          xmlns:jcr="http://www.jcp.org/jcr/1.0"
    jcr:primaryType="cq:ClientLibraryFolder"
    categories="[mysite.base]"
    dependencies="[cq.jquery,granite.utils]"
    embed="[mysite.icons]"/>

🤔 Common Confusions

🚨 Common Production Issues

✅ Best Practices

🏛️ Architect's Note

💬 Frequently Asked Questions

🎯 Key Takeaways

🔗 Related Topics

🎯 Practice this topic in interviews

↗ Where this topic fits