Revision 507851 of Extensions

<div>
  <p><strong>Extensions</strong> add new functionality to Mozilla applications such as Firefox, SeaMonkey and Thunderbird. They can add anything from a toolbar button to a completely new feature. They allow the application to be customized to fit the personal needs of each user if they need additional features, while keeping the applications small to download.</p>
  <p>Extensions are different from <a href="/en-US/docs/Plugins" title="Plugins">plugins</a>, which help the browser display specific content like playing multimedia files. Extensions are also different from <a href="/en-US/docs/Creating_OpenSearch_plugins_for_Firefox" title="Creating_OpenSearch_plugins_for_Firefox">search plugins</a>, which plug additional search engines in the search bar.</p>
</div>
<div class="row topic-page topicpage-table cleared">
  <div class="section">
    <h2 class="Documentation" id="Documentation" name="Documentation">Documentation</h2>
    <h3 id="General_(applicable_to_all_Mozilla_apps)">General <small>(applicable to all Mozilla apps)</small></h3>
    <dl>
      <dt>
        <a href="/en-US/docs/Setting_up_extension_development_environment" title="Setting_up_extension_development_environment">Setting up an extension development environment</a></dt>
      <dd>
        A few essential setup tips that make extension development easier.</dd>
      <dt>
        <a href="/en-US/docs/Extensions/Bootstrapped_extensions" title="Extensions/Bootstrapped extensions">Bootstrapped extensions</a> {{gecko_minversion_inline("2.0")}}</dt>
      <dd>
        How to create extensions that can be installed, uninstalled, and upgraded without requiring an application restart.</dd>
      <dt>
        <a href="/en-US/docs/XUL_School" title="XUL School">XUL School Tutorial</a></dt>
      <dd>
        A comprehensive extension development tutorial.</dd>
      <dt>
        <a href="/en-US/docs/Building_an_Extension" title="Building an Extension">Building an Extension</a></dt>
      <dd>
        Introductory tutorial for creating a basic extension.</dd>
      <dt>
        <a href="/en-US/docs/Extensions/Inline_Options" title="Extensions/Inline Options">Inline options</a> {{gecko_minversion_inline("7.0")}}</dt>
      <dd>
        How to use the new preference UI that appears inline in the Add-on Manager window starting in Firefox 7.</dd>
      <dt>
        <a href="/en-US/docs/Security_best_practices_in_extensions" title="Security best practices in extensions">Security best practices in extensions</a></dt>
      <dd>
        Guide for developers to ensure users of the extension are safe.</dd>
      <dt>
        <a href="/en-US/docs/Extensions/Performance_best_practices_in_extensions" title="Extensions/Performance best practices in extensions">Performance best practices in extensions</a></dt>
      <dd>
        How to build extensions that perform well and don't hurt application performance.</dd>
      <dt>
        <a href="/en-US/docs/Extensions/Extension_etiquette" title="Extensions/Extension etiquette">Extension etiquette</a></dt>
      <dd>
        General extension best practices to make the user experience as good as possible.</dd>
      <dt>
        <a href="/en-US/docs/Extension_Packaging" title="Extension_Packaging">Extension packaging</a></dt>
      <dd>
        How to package your extension for downloading and installation.</dd>
      <dt>
        <a href="/en-US/docs/XUL" title="XUL">XUL</a></dt>
      <dd>
        Documentation for XUL, the markup language used for describing user interfaces for Mozilla extensions.</dd>
      <dt>
        <a href="/en-US/docs/Performance" title="Performance">Performance</a></dt>
      <dd>
        Performance guides and utilities to help you make your add-on perform well (and to play nicely with others).</dd>
      <dt>
        <a href="/en-US/docs/Installing_extensions" title="Installing_extensions">Installing extensions</a></dt>
      <dd>
        How to programmatically install extensions.</dd>
      <dt>
        <a href="/en-US/docs/Submitting_an_add-on_to_AMO" title="Submitting_an_add-on_to_AMO">Submitting an add-on to AMO</a></dt>
      <dd>
        How to distribute your add-on using the AMO web site.</dd>
      <dt>
        <a href="/en-US/docs/Extension_Frequently_Asked_Questions" title="Extension_Frequently_Asked_Questions">Extension Frequently Asked Questions</a></dt>
      <dd>
        Common questions and answers about extension development.</dd>
    </dl>
    <h3 id="Application_Specific">Application Specific</h3>
    <p><a href="/en-US/docs/Extensions/Firefox" title="Extensions/Firefox"><strong>Firefox</strong></a></p>
    <p><a href="/en-US/docs/Extensions/Thunderbird" title="Extensions/Thunderbird"><strong>Thunderbird</strong></a></p>
    <p><a href="/en-US/docs/Extensions/SeaMonkey" title="Extensions/SeaMonkey"><strong>SeaMonkey</strong></a><br>
      <a href="/en-US/docs/Extensions_support_in_SeaMonkey_2" title="Extensions_support_in_SeaMonkey_2">  Extensions support in SeaMonkey 2</a></p>
    <p><strong><a href="/en-US/docs/Extensions/Mobile" title="Extensions/Firefox_on_Android">Firefox for Android</a></strong></p>
    <p><a href="https://starkravingfinkle.org/blog/2009/05/resources-for-fennec-add-on-developers/" title="https://starkravingfinkle.org/blog/2009/05/resources-for-fennec-add-on-developers/"><strong>Fennec</strong></a> (mobile browser)</p>
    <p><span class="alllinks"><a href="/en-US/docs/tag/Extensions" title="tag/Extensions">View all pages tagged with "Extensions"...</a></span></p>
  </div>
  <div class="section">
    <h2 class="Community" id="Community" name="Community">Community</h2>
    <ul>
      <li>View Mozilla extension development forums...{{DiscussionList("dev-extensions", "mozilla.dev.extensions")}}</li>
      <li><a class="link-irc" href="irc://irc.mozilla.org/extdev">#extdev IRC channel</a></li>
      <li><a href="https://forums.mozillazine.org/?c=11">MozillaZine forum</a></li>
      <li><a href="/devnews/index.php/categories/about-addons" title="https://developer.mozilla.org/editor/fckeditor/core/editor/devnews/index.php/categories/about-addons/">about:addons newsletter</a></li>
      <li><a href="/web-tech" title="https://developer.mozilla.org/editor/fckeditor/core/editor/web-tech/">Mozilla's Web-Tech blog</a></li>
      <li><a href="https://mozdev.org/mailman/listinfo/project_owners">mozdev project owners</a></li>
      <li><a href="https://planet.mozilla.org/" title="https://planet.mozilla.org/">Planet Mozilla</a></li>
      <li><a href="/en-US/docs/Extensions/Community" title="Extensions/Community">Other community links...</a></li>
    </ul>
    <h2 class="Tools" id="Tools" name="Tools">Tools</h2>
    <ul>
      <li><a href="/en-US/docs/DOM_Inspector" title="DOM Inspector">DOM Inspector</a> - inspect DOM, CSS, and XBL (Firefox and Thunderbird)</li>
      <li><a href="https://www.hacksrus.com/~ginda/venkman/" rel="external nofollow" target="_blank" title="https://www.hacksrus.com/~ginda/venkman/">Venkman</a>, a JavaScript debugger (<a href="https://addons.mozilla.org/en-US/firefox/addon/216" rel="external nofollow" target="_blank" title="https://addons.mozilla.org/en-US/firefox/addon/216">Firefox</a>, <a href="https://addons.mozilla.org/en-US/thunderbird/addon/216" rel="external nofollow" target="_blank" title="https://addons.mozilla.org/en-US/thunderbird/addon/216">Thunderbird</a>)</li>
      <li><a class="link-https" href="https://builder.addons.mozilla.org/" title="https://builder.mozillalabs.com/">Mozilla Add-on Builder</a></li>
      <li><a class="link-https" href="https://addons.mozilla.org/en-US/firefox/addon/7434/" rel="external nofollow" target="_blank" title="https://addons.mozilla.org/en-US/firefox/addon/7434/">Extension Developer's Extension</a> a suite of development tools</li>
      <li><a href="https://www.gijsk.com/" rel="external nofollow" target="_blank" title="https://www.gijsk.com/">Chrome List</a> view files in chrome:// (<a href="https://addons.mozilla.org/en-US/firefox/addon/4453" rel="external nofollow" target="_blank" title="https://addons.mozilla.org/en-US/firefox/addon/4453">Firefox</a>, <a href="https://addons.mozilla.org/en-US/thunderbird/addon/4453" rel="external nofollow" target="_blank" title="https://addons.mozilla.org/en-US/thunderbird/addon/4453">Thunderbird</a>)</li>
      <li><a href="https://ted.mielczarek.org/code/mozilla/extensionwiz/" rel="external nofollow" target="_blank" title="https://ted.mielczarek.org/code/mozilla/extensionwiz/">Extension Wizard</a> a web-based extension skeleton generator (Firefox and Thunderbird)</li>
    </ul>
    <p>... <a href="/en-US/docs/Setting_up_extension_development_environment#Development_extensions" title="Setting up extension development environment#Development extensions">more tools</a> ...</p>
    <h2 class="Related_Topics" id="Related_Topics" name="Related_Topics">Related Topics</h2>
    <ul>
      <li><a href="/en-US/docs/XUL" title="XUL">XUL</a>, <a href="/en-US/docs/JavaScript" title="JavaScript">JavaScript</a>, <a href="/en-US/docs/XPCOM" title="XPCOM">XPCOM</a>, <a href="/en-US/docs/Themes" title="Themes">Themes</a>, <a href="/en-US/docs/Developer_Guide" title="Developing_Mozilla">Developing Mozilla</a></li>
    </ul>
  </div>
</div>
<p> </p>