Tor Browser

Tor is a derivitave of Mozilla Firefox, accessing Tor (The Onion Router). The browser allows one to access the "dark web;" difficult to be traced by providers. However, such has led Tor to be used in illicit activities, giving Tor a reputation similar to 4chan for their similar anonymity and illegal or otherwise dangerous content.

Firefox Derivatives
TenFourFox

Waterfox

Basilisk

Pale Moon

K-Meleon