Go to https://magicmockups.com and select any image. Upload a screenshot of your website or app or simply enter its URL.
Here I’m going to create a mockup for HostOnNet.com, I’ve selected the iMac and iPad mockup environment and uploaded images for both devices. You can use https://www.screenshotmachine.com to capture screen of different device.
Now we can download the mockup in different size.
Here is the mockup I just created.