There are numerous ways (software, web application and web browser extensions) to take screenshot of a webpage and save it as static image. And then you upload it on your server or any image sharing website and use it on your blog or website.
What you do when you need to take screenshot of webpage to use or embed it on your blog or website and the screenshot should get auto updated when that webpage’s design or content get change or modified.
If your blog is on WordPress platform then you might have noticed that when someone comment on your blog and if they mention their website link with their comment, then in comment moderation page when you hover over their website link it will show preview of their website in a small screenshot. So in case if you don’t know then let me tell you that those are dynamic screenshots, they get updated almost every day.
So in case if you need screenshot for your blog or website which can get updated automatically then all you need to do is enter the website or webpage URL of which you would like to have dynamic screenshot and also you can mention what should be the width of that screenshot. Size of the screenshot will be in the ratio of 1.3:1 (where 1.3 is width and 1 is height).
Dynamic Screenshot Generator
You can use the above code to embed or use URL to link the screenshot anywhere you want. Click here to see a sample screenshot. It will work with almost any website or webpage you want.
In case if you are going to add it in a PHP code then you can use the below URL and change WEBPAGE_URL with the URL of the webpage of which screenshot you want to take (URL should start with http or https).
http://s.wordpress.com/mshots/v1/<?php echo urlencode('WEBPAGE_URL') ?>?w=400
These screenshot will be served by WordPress.com server. It may happen that if a webpage is being called for the first time or after long time then it may take time to appear or maybe after 3-4 tries. Your image will be generated in JPG format but when you will save that screenshot as image in your computer then extension name will change to PNG but format remain same (as JPG) and this is the user-string they are using (at the time of writing this post) to generate the screenshot:
Mozilla/5.0 (X11; U; Linux x86_64; en-us) AppleWebKit/531.2+ (KHTML, like Gecko) Version/5.0 Safari/531.2+ WordPress.com mShots; http://support.wordpress.com/contact/