This page includes some of the tools I use in my daily work with online government information. I don't necessarily endorse any of these over other similar tools available, but these work quite well for me. If you're interested in closely following changes to federal pages, give them a try. (And please feel free to let me know if there are similar/better tools I should try!)
Diffchecker -- helps compare the text of documents/images to see what changes have been made
Check My Links -- Chrome extension that crawls a webpage and identifies broken (in red) and redirected (in light green) links. I use this for my extensive GovSpeak site, and it's extremely helpful in identifying federal websites that are unavailable.
Update Scanner -- Firefox extension that lets you monitor webpages to identify changes
Wayback Machine -- in addition to capturing a page (as seen on the "what can you do" tab of this guide), Wayback lets you view webpages as they were on the day captured. This is especially helpful when you're trying to determine if changes have been made to a webpage.
After entering a url to search, the results page will show a calendar if the page has been captured previously. The blue dots generally indicate successful captures, so find the blue dot closest to the date of interest and hover your mouse until you see timestamps appear. Click a timestamp to view the archived page.
