Firefox is rich with plugin. There are many choice for make the firefox running through proxy. I will write about the most popular of firefox proxy plugin .

Foxyproxy is a set of proxy management tools for Firefox. This tools can also use with Thunderbird, Seamonkey, and Songbird.

The main fitur of foxyproxy :

Animated statusbar/toolbar icons show you when a proxy is in use

Define multiple proxies

Define which proxy to use (or none!) for arbitrary URLs using wildcards, regular expressions, whitelists, blacklists, and other conveniences

No more wondering whether a URL loaded through a proxy or not: FoxyProxy optionally logs all URLs, including which proxy was used (if any), which pattern was matched, timestamps, etc.

Out-of-the-box support for Tor with the unique Tor Wizard - zero configuration!

Temporarily or permanently dedicate all URLs to go through a particular proxy

Temporarily or permanently disable use of a proxy
Automatically add blocked sites to a proxy and have them reload through the proxy

Optional status bar information about which proxy is currently in use

Complete Proxy Auto-Config (PAC) support Download a link using one of your defined proxies with a simple right-click (coming soon)

Unobtrusive presence, stable execution, premier support

Optionally force Firefox to perform DNS lookups through a SOCKS4a/5 server. Note that Firefox without FoxyProxy always performs DNS lookups through a SOCKS5 server if you’ve defined one. Only with FoxyProxy can you instruct Firefox to not use defined SOCKS5 servers for DNS lookups.

FirexFox Plugin: SwitchProxy Tool

SwitchProxy Tool is a Mozilla tool you can use to organize all your proxies. You can add, edit and remove them from a single master list. When you need to use one, just select it from the list and click apply.

It also has an Anonymous Proxy feature. An anonymizer uses a list of proxies setting that it randomly switches between at defined intervals. Many people used anonymizers to shield their IP address and protect themselves from hackers, online tracking, harvesting and other website snooping techniques.