Website Thumb Generator can be used to create website thumbnails for use within an application. Analyzo has listed some popular thumbnail generators.
Bitpixels creates thumbnails of websites without having a developer to write any code or use a script or plugin. It is a simple html code that generates the thumbnails. BitPixels takes a picture of a URL, and serves back a thumbnail image. It runs on Google Cloud for fast, reliable service.
Pagepeeker Generates screenshots in a matter of seconds. Rendering starts immediately and is finished quickly. Using two different rendering techniques, they ensure that the screenshots and website thumbnails are always generated properly. If one method fails, the second always succeeds.
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. It is adaptable to creative uses such as svg rendering and IOS and Android integration. Available in github Bash, PHP and Python.
SnapCasa is a free website screenshot generator. Free thumbnails are available in four sizes, they do not include any watermarks or ads, and there are no limits on usage. Snapshots are captured fast and updated on a regular basis. There are no limitations in the number of screenshots you can capture. Use on multiple websites. Claims to have 99.9% uptime.