janus-ua by Firefox user 12702102

If you want to be anonymous, you can follow two divergent strategies:

a) Refuse to state your name. When the majority of people *do* identify themselves, you put yourself into a small subcategory, making it relatively easier to identify you

b) Use a codename. Unless you use different codenames with each person, all you've done is change your name. Others can still talk about you behind your back by using that codename.

This plugin falsifies your user agent in a novel way: to make you less suspicious, it reuses the same false user-agent each time you talk to the same website; to make it harder for marketing companies to cross-correlate your identity, a different user agent is used on each web site.

One way that marketing companies track you is by correlating HTTP headers between websites. With this plugin, every time you visit the same site you'll present the same unique User-agent string. Any requests from that page that are made to other domains will send a different unique user string. This should make correlating identities across domains much harder.

The user agents are randomly generated by a repeatable PRNG. The domains are hashed with different coefficients each time the browser starts. User agents are modeled on real user agents, but won't make sense if you look closely: you'll probably end up being both Firefox and Chrome to some web sites, or Safari running on Linux. But, if a web site is just looking for "does it contain the right format string for Chrome" to validate your User agent, you'll fly under the radar totally undetected.