With screenshot generator API you can take screenshots of a website/app on a mobile, tablet or desktop using a simple API. Analyzo has listed the services that can be used for this functionality.
Url2Png can capture a high quality screenshot of any website/url using a simple API. This is a great way to show thumbnails of a website within your application.
Page2Images captures an image from the provided url. This service can also be provided via an API which can be used to provide thumbnails of different sizes within a mobile or web application.