Firefox 1 (en-US) 21.0

Legacy version of Firefox that's no longer supported

  • Category:

    Web browsers

  • Version:

    (en-US) 21.0

  • Works under:

    Windows 7 / Windows 2003 / Windows Vista / Windows XP / Windows 2000 / Windows 8

  • Program available in:In English
  • Program license:Free (GPL)
  • Vote:
    7.1 (624)

Firefox is a downloadable Web browser which users can use in place of the Web browser that comes with their operating system. While many users will find built-in browsers such as Internet Explorer sufficient for their needs, Firefox features a number of enhancements that speed up your browsing. Firefox can load websites up to three times quicker than it's competitor, meaning users can spend more time reading and less time staring at a blank white page.

Packed Full of Features

Even though this is an older version of Firefox, it still contains many of the same features as newer versions of the browser. For example, this version of Firefox includes tabbed browsing, a feature that allows you to open up multiple websites in a single window. However, keep in mind that this version of Firefox can suffer from a memory leak when too many tabs are open at one time. Another feature is the built-in pop-up blocker, which will eliminate almost any advertisements from appearing on your screen. In addition, if you want to remain undetected on the Web, you can use the browser's Private Browsing feature. This feature won't save your website history or any cookies, making it impossible for anyone to track what you've been doing in the browser. This version of Firefox gives its users full customization over what features they want. From Firefox's Options menu, you can enable or disable any feature and create a custom browser that is perfectly tailored to your needs.


  • Can load any website in a matter of seconds
  • High levels of customization allows users to configure the browser however they want
  • Includes an array of privacy features


  • This version of Firefox is no longer supported by Mozilla
  • Numerous bugs and security risks exist in this version of Firefox. Users should use this older version at their own risk.

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User Opinions on Firefox 1