Xenu Link Sleuth
If you have any links on your website, you will know the problem of stale links. Every now and then visitors to your site will click on a link and face a "404 - Page Not Found" or similar error message. You simply can't prevent that. Websites go away, pages get moved or renamed. Nothing remains constant, except change.
Yet, if there are too many stale links, or if important pages disappear for a long time without the linking page getting updated that won't leave a very good impression with your visitors. That's why you have to try to keep broken links to a minimum - and that's where Xenu Link Sleuth by Tilman Hausherr comes in. I run it regularly to track down all missing pages and the pages that refer to them. It produces tables of broken and functional pages and a convenient list of all pages on a site. It's fast and it's free. Warmly recommended!