Test Size is a tool that will be of use to web developers and designers everywhere. In a nutshell, it will let them test any page that they are designing on the spot, and see how it would be rendered in different window sizes.
The actual implementation couldn’t be easier, as all that you have to do is enter the URL that you want tested, and choose the size along with the width and height. The screen will be generated in front of you eyes, and you will be able to switch from one size to the other by hitting the space bar. You can zoom in and out very easily, as pressing “+” and “-” or the arrow keys will have that effect.
The system is so easy to employ that you might be thinking that it will only be of use to young developers, but I think that the ease of use makes it suitable to pros who have almost no seconds to spare from assignment to assignment, and who need a quick way out of conundrums.
TestSize.com In Their Own Words
“Test any web page in any window size.”
Why TestSize.com It Might Be A Killer
What further functionalities could be added in order to make it even more versatile?
Some Questions About TestSize.com
Are all browsers supported? 
