The above image is a thumbnail of Free Nuts, created by Thumboo.
Thumboo is a website which lets you create an instant thumbnail online quickly and free. You just need to input a URL of any website or webpage, and the thumbnails will be generated quickly.
The generated thumbnail image will be available in 4 sizes: Small(150×100), Medium(200×150), Large(300×250) and Huge (full size). The thumbnail of any size is available for download in JPG format.
Besides, there is also a PHP code for the thumbnail of any size, which means you can paste the code in your website template, and the thumbnail will be displayed accordingly. You are able to sign up in Thumboo, so that you will get an API key, which will allow you to change the website URL directly in the PHP code, and no need to visit the Thumboo website.
All the thumbnail images generated by PHP code will be linked back to Thumboo homepage, that’s why I do not like to use the PHP code. 
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