As my favourite web browser, Firefox, with the powerful extensions, (in my opinion) no other web browser is better than it. There are a lot of web browsers based on Chromium or using WebKit engine. Namely Google Chrome (based on Chromium), Opera (WebKit engine), Safari (WebKit engine), Konqueror (KDE web browser), Epiphany (currently called Web, GNOME web browser), and other less popular web browsers such as Midori, QupZilla, etc.
However, Firefox uses another layout engine, that is Gecko. That is why the rendering of the webpages may have some differences comparing to the WebKit engine. For the web developers, they can always see the differences.
Firefox is able to open a new instance with a different profile. That means a user can run the Firefox with a new and clean profile without any addon together with his or her default profile. This can be done by using the command-line such as
firefox -no-remote -P profileName
The profile can be created by
firefox -no-remote -ProfileManager
With this, the user can install Firefox Beta, Aurora, and Nightly, then run the different instances through the command-line. This is fantastic.
Interestingly, because of the branding issue of Mozilla, Firefox is re-branded as BurningDog in gNewSense and Iceweasel in Debian. And There is another re-brand from GNU project, that is GNU IceCat (formerly GNU IceWeasel, which is different from Debian’s Iceweasel). Moreover, there are specially customised web browser for anonymous surfing which use Firefox as well. For instance, Tor Browser Bundle and JonDoBrowser.
In Arch Linux, if you do not want to use command-line to run the different Firefox and its variants with different instances, then you can install GNU IceCat and Pale Moon from AUR.
Why do I need to many instances? One of the reasons I am doing so is because of the proxy. Because sometimes I want to use Tor for anonymous browsing temporary. This cannot be solved by simply using FoxyProxy. Though FoxyProxy can use different proxies depending on the URL pattern, yet I just want to surf several pages anonymously temporary in another window. At the same time, the other windows remain using default proxies or no proxy. Because of this, only new instance of Firefox can be solved. Because of this, for the ease of the surfing, I installed other variants of Firefox. Good!