Best Free Web Site Link Checker

Virtually all websites have dead or broken links in the same way that all software has bugs. Mistakes happen, content changes, file names and locations change, and external links change. And until you've checked links for some period of time, and learned what breaks them, you're likely to repeat the classic mistakes on a regular basis. ;-)

Link checkers work much like a search engine spider. They "crawl" your website looking for internal and external links that are broken. Crawling is recursive, meaning that the spider builds a tree of links leading from page to page until all branches have been explored. Spidering continues until it reaches a defined termination point. For example, when all internal branches have been examined, or when all first level external links have also been examined. A good link checker also produces broken-link reports that enable you to determine where the broken link is located, and why the link is broken.

Note: Your server may be configured to block "robots" (search engine spiders) by using robots.txt of .htaccess files. If so, you won't be able to scan for broken links unless you can configure your link checker to lie to the server, or remove temporarily the blocks from the server. Some scanners, Xenu's Link Sleuth for example do not respect "no robots" file so they will work even though robots are "blocked".

Update: Commenter Hank Friedman recently pointed out LinkChecker which quickly rose to the top of this category.

LinkChecker has all the features I ever wanted in a link check program, and more. Most importantly, it provides the parent URL, which makes it easy to go directly to the file/page where a broken link is located to fix it. Easy to read summary results for each link checked. The page title, info, warning, and result (404/303/etc.) response from the server are also presented. It's easy to set the recursion depth (how many sub-folders get checked).

LinkChecker can also be used from the command line. There is a powerful set of command-line options that can also be used to edit a personal configuration file for LinkChecker. You should be able to tailor a scan to meet just about any check you can imagine.

Xenu's Link Sleuth: I used Xenu for many years. It's simple, small, fast and accurate. It takes a while to learn how to use Xenu's Link Sleuth, and it can be daunting to understand the reports, but if you stick with it you'll come to appreciate the excellent job it does. It's main shortcoming is not reporting the parent page where each broken link is discovered.

The Link Evaluator extension for Firefox works well, but it only checks one page at a time. However it's useful when you want to do a quick check.

Web-based Alternatives: Link checking is a natural fit for a cloud solution. An online service bypasses your ISP for the most part, and produces quicker results.

Hat tip to commenter Riss for this one: Online Broken Link Checker has an advantage in presenting only definitely broken links, without a report on all the other categories, including non-broken links. For each bad hyperlink it finds you can open a page that contains the source of the page where the broken link is located, and highlights the actual HTML tag that contains the non-existent link.

The free version currently limits the number of links checked to 3000. Since it checks both external as well as internal links, that is not enough for all -- mine for example -- sites. There is a no-limit commercial version of this checker available that allows to validate sites of any size (even huge ones) without page limitations.

Link Valet by Web Design Group spiders your website, like a search engine would, and provides a very nice broken link report. Broken links are listed by page location so it's easy to find and fix them. There is a recursion (depth of spidering) limit, but the report includes a list of pages that were not checked, so you can extend link checking deeper if you want.

Google Webmaster Tools reports the errors that the Google spider finds when it crawls your website. You'll find the link errors (not found) under "Web crawl errors" in the "Overview" section of the "Dashboard". The beauty of the link error report is that the details page shows the page(s) that contain the broken link(s).

The FreeFind search engine crawls your website to power their free site search. When finished FreeFind provides a very complete spider report, which shows all the broken links. The page that contains a broken link is not listed though, so it often takes some sleuthing to figure out where broken links are located.