Are there analogues of the IETab add-on for firefox, but other browsers?

Question

Opera

I want to see sites in firefox as they look under other browsers, in other words, I'm looking for add-ons for the fox ala ChromeTab, OperaTab, etc.

Answer 1

I, of course, in the context of the question posed, I will be wrong. But still, do not use IETab, IETester and other stray. The work of IE directly depends on the system libraries and on the environment. It is very easy to run into the fact that in the emulator the result will still be different from stand-alone IE.
Why do you want to watch everything in FF?
Put a zoo of browsers, maybe. start a virtual machine with XP for more confident viewing in IE 7, 8. See the originals.
For IE, you can use compatibility modes. That is, your 9th IE can show sites as 7th and as 8th.
FF can be downloaded separately older versions. Although, IMHO, FF is worth checking out the 3rd and last one. Well, the 2nd one, there were some specific troubles ... Again, if the client needs it.

Answer 2

Here is for Chrome:
chrome.google.com/webstore/detail/hehijbfgiekmjfkfjpbkbammjbdenadd