Utilu Mozilla Firefox Collection is a utility developed by Utilu that contains multiple versions of the free web browser Mozilla Firefox, which are standalone so they can be used at the same time. This is useful for web developers.
In Utilu Mozilla Firefox Collection you can quickly see how your websites look when rendered using different versions of the Gecko render engine. You can specify the filenames or locations (URLs) to open in multiple installed versions of Mozilla Firefox.
Also the versions to open can be chosen. Filenames or URLs that include spaces must be enclosed in quotes. Multiple filenames or URLs may be used by separating them by spaces. This will result in multiple tabs being opened.