How can I automate taking screenshots of 10,000+ pages? I am using mac OS X El Capitan and need to find a way to automate taking screenshots of 10,000 or more pages. The problem with all current solutions is that the webpage requires me to login using my email/password combo. The webpage is CSS/Java and the screen requires you to scroll down in order to view the entire page, all current solutions are not capable of scrolling down to view the whole page and only screenshot the visible portion. The second problem is that a certain combination of clicks needs to be pressed in order to go to the next page. I have considered using a "Cross browser testing" solution since some are capable of screenshots. The problem with that is that none are free and none are capable of entering login/password authentication. Are there any softwares/solutions that would allow me to screen capture 10,000 pages without manually doing it?
Write a script,  use something like pageres.   

Check out this list , in the "Screenshot Utilities" section, you'll find many links to utils, APIs and web services.