Website resolution tool (aka site resolution tester) provides the ability to test your website with different screen resolutions.
It features a handy list of popular resolutions for desktops, laptops, tablets and high-end phones.
Alternatively resolution could be entered manually.
When 'in browser' checkbox is checked resolution corresponds to the screen resolution of the monitor and some space is allocated for
the task bar as well as web browser controls and borders.
Otherwise it is resolution of the web page itself.
The later is useful for testing your website with mobile device resolutions, since mobile devices commonly render sites in full screen. Mobile and tablet resolutions are dimensions of the browser viewport.
Since this tool renders pages completely in your browser it could even be used to test websites hosted on your local computer or on internal network.