## Firefox

[Firefoxes](https://github.com/omgmog/install-all-firefox) is a shell scripts that will install all major versions of Firefox on OS X, and set up separate profiles so you can use them simultaneously. Currently it installs:

 - Firefox 2.0.0.20
 - Firefox 3.0.19
 - Firefox 3.5.9
 - Firefox 3.6.28
 - Firefox 4.0.1
 - Firefox 5.0.1
 - Firefox 6.0.1
 - Firefox 7.0.1
 - Firefox 8.0.1
 - Firefox 9.0.1
 - Firefox 10.0.2
 - Firefox 11.0
 - Firefox Beta
 - Firefox Aurora
 - Firefox Nightly
 - Firefox UX Nightly

You can set it up so it only installs the specific versions you want.

Optionally, the script can install Firebug for each version of Firefox too.

It will also set icons that contain the version number:

![](http://gkoberger.net/images/notepad/firefoxes.png)

## Safari

For Safari, check out [Multi-Safari](http://michelf.com/projects/multi-safari/).

## Chrome/Chromium

For Chrome/Chromium, install any version you want, change the app name from `Chromium.app` to e.g. `Chromium 19.app` for clarity, then [disable auto-updates](http://dev.chromium.org/administrators/turning-off-auto-updates) for that version.

## Opera

Download old Opera versions here: http://mac.oldapps.com/opera.php

## IE

Get VirtualBox and then run [this `ievms` script](https://github.com/xdissent/ievms). It will automatically download legal Windows images for testing purposes and set up virtual machines for every IE version you need.