Some very useful Active Bookmarks are listed below.
You can add any of these Active Bookmarks to your browser, if you are using Internet Explorer, simply right click on the bookmark and select add to favorites.
Way Back Machine
This will take you to the internet archive of the web site you are on.
View the who is of the page you are on.
Load Time Test
Test the load time of the page you are on.
The Free Dictionary
Highlight a word then look it up in the student dictionary.
Screen Size Test
Test the screen size of the page you are on.
Check your pages for copyright infringement.
Google's Mobile friendly test application.