Font Replacer is a Firefox extension, can replaces the current font in Firefox. The usage is very simple: Go to the preference of this extension by opening the Add-ons Manager. Two textboxs will appear, one for the source fonts, the other for the replacements.
This add-on is useful for designers which have installed too many fonts. Some web pages look ugly when the font used is present in the current system, but not designed for plain text, like Helvetica Neue on Windows.

Requirements:
* Firefox
* SeaMonkey

The license of this software is Free, you can free download and free use this browser plug-ins software.