Daily Scrape PDFs to see if any have changed

What I am trying to do is develop a system that automatically queries different web sites to determine if the page or pdf online has changed (or at least what the date it was posted or version or something I can compare to my records). Department of Transportation (DOT) websites post lists of which companies and products are approved for use and they change these without telling us. Thus, I have to check fifty sites all the time and read the whole page to determine if I need to update my records. If I could get some system just to check daily and alert me to which ones have changed, that would really save me time and keep me on top of the DOT situations. The sites are all different, so I know we would run into a lot of different scenarios. The bulk I need to check would be formatted as a pdf file you open by clicking on a link. ## Deliverables I am envisioning a web page that only I can access that has a table with the state, link and status on it. I would want it to update daily. I have two links below, which represent typical state operating procedures. One is a web page with a table of information. The other is a page where I am interested in one particular pdf. [login to view URL] On this page, select Erosion Control Blankets for one table of interest and Turf Reinforcement Mats for the second table of interest. The result of the query is what I want to see if it has changed. Since this is a query, I do not know how this will work. The second is here: [login to view URL] I need the to check the pdf for Erosion Control Matting, 626.02. That file’s address is: [login to view URL] I just need to know if they have changed from the last check.