XUL (XML User Interface Language)

XUL is a web programming language that you can use to build Firefox plugins.

XUL is a web programming language that you can use to build Firefox plugins.

XUL was created by the Mozilla project, an open source collaboration that also created, and maintains, the Firefox browser. XUL is to Firefox what HTML is to webpages, meaning that you use XUL to build interface elements for the Firefox browser. Want a window to popup that asks the user to pick between three answers: Yes, No, Maybe?

In HTML you might write:

<div id="popup">
<input type=”radio” name=”answer” value=”Yes” />
<input type=”radio” name=”answer” value=”No” />
<input type=”radio” name=”answer” value=”Maybe” />
<input type=”submit” name=”submit” value=”Submit” />

In XUL you would write:

<?xml version="1.0"?>
<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
<window id="vbox example" title="Example 3...."
<button id="yes" label="Yes"/>
<button id="no" label="No"/>
<button id="maybe" label="Maybe"/>

XUL, like HTML, relies on a combination of markup, CSS, and JavaScript to do its magic, and is relatively easy to pick up for anyone familiar with frontend web development.

XUL powers all the wonderful Firefox plugins that we love. Add-ons like Firebug or Adblock. Have an idea for a cool Firefox plugin for your site? Something neat like a dictionary that allows you to look up tech terms on Skillcrush from any website in the world? Check out Mozilla’s XUL School (that’s zool school) or Gina Trapani’s great blog post on how to get started.

Cocktail Party Fact

The name Mozilla was originally the codename for the Netscape Navigator project way back in the mid 1990s (remember that awesome web browser that most of us used to first access the web?). The name is a variation of Godzilla, which is also the inspiration for the reptilian monster that is now used as the Mozilla Foundation’s logo.

In 1998, Netscape released all of its browser source code under an open source license and called it Mozilla, after the browser’s original codename. That codebase has been used to develop two popular browsers: Firefox and Thunderbird.