Screensiz.es is a website that lists the important data about the screens of widely-used mobile + tablet screens and monitors. When developing mobile (web) apps or responsive layouts, knowing the major screen-sizes and resolutions help a lot on deciding the dimensions for the layout.
It is possible to find the operating system used, physical size, resolution, PPI and pixel-density values. Also, devices can be sorted by popularity which is a good way to decide which resolutions are your target.
Website: http://screensiz.es/
