Responsinator - Designed to test responsive websites on different devices.
HRC – Hotkey Resolution Changer - If you are looking for a sumptuous desktop application that will overcome every bit of your need to adjust the brightness, resolution, and color contrast of your screen, then Hotkey Resolution Changer can be a smart option for you.
Responsive Viewer - View multiple screen dimensions in one view
Display Resolution Manager - Display Resolution Manager is an easy-to-use software that is providing a straightforward way to play around with your screen resolution and color settings.
LT Browser by Lambdatest - LT Browser is a free dev friendly browser for developers and testers. You can see mobile view of website on different screen sizes and resolution on 50+ pre installed view ports. You can build, test and debug your website faster then ever.
SwitchResX - SwitchResX is a tool designed to manage resolutions of all your monitors and HDTVs.