Anyone who has ever spent time on a
link building campaign knows how much work it is to create content, build a pitch list and contact people to see about getting the link. Nonetheless, links are essential currency in the land of search engine optimization. I'm willing to bet if you had a chance to pick up links without much more than a friendly email you'd jump on it, right?
Matt Cutts points out that very chance in a post on his blog. In "
Free links to your site," Matt talks about a new feature that's been added to Google's
Webmaster Central. According to Matt, the new feature "lets you see who is linking to your 404 pages."
Why would that matter? Matt explains:
The simple reason is that if someone is linking to a non-existent page on your site, it can be a bad experience for users (not to mention that you might not be getting credit for that link with search engines unless you're doing extra work). Some of the easiest links you'll ever get are when people tried to link to you and just messed up.
It would be trivial to mail some of these people and say "Hey, I noticed you linked to my site (thank you!) but the link is broken, so users will get a 404 page. Would you mind changing your link on page A to point to the right page, which is url B?" When the other site fixes their link, their visitors find your site directly, plus all search engines can follow those links and give you credit for them. Converting 404 links to links to the right pages converts bad links to free direct text links for all.
So how do you get this info? Here's a quick step-by-step pictorial.
First you'll need to head over to
Google Webmaster Central. Once you're there, look for the link that says "
Sign in to Webmaster Tools."

If you don't have a Webmaster Tools account, you'll need to take a few moments to set one up. If you do have a Webmaster Tools account, you'll be taken to the list of domains you've activated. Go ahead and pick the one you want to check out.

Once you've selected your site, you'll need to scroll down to the "web crawl errors" section and look for the link to view your "not found" pages.

Google will provide you with a list of URLs that are feeding 404 errors to sites that link to you. As you look through the list, you'll notice a column that says "linked to." That column will tell you how many sites are linking to the bad page.

This is an important column to take note of. In fact, if you click on the link there, you'll get a pop up window that shows which site is linking to the broken URL.

Chances are, you'll have quite a few URLs that only have a single link to them. This means someone simply typed the URL in wrong when they were linking, or they cut and pasted a dynamic URL or a URL that contains a session ID. While it's still a good idea to drop these folks an email and ask them to update their link to one that works, it's the URLs that have lots of incoming links that you really need to worry about.
These are links that were likely perfectly good at one time but for whatever reason are now broken. Chances are good you'll want to fix this issue on your end by putting the web page back at that address or setting up a 301 redirect rather than taking the time to contact everyone who is linking in and asking them to make the change.
Take Advantage of the Downloads
It's a good idea to take note of Google's "download this table" option for this report. It's a great way to have a checklist of broken URLs you need to take a look at.
It's also a good idea to click the "download all sources of errors on this site" option so you can have a spreadsheet of all the sites linking to you with broken links. This will give you a list of web sites to email with updated linking information as you have free time.
Building links is hard work. This tool from Google will make it a little easier to make sure you're getting full credit for the links people have willingly given you. After all, there's no easier link to get than the one that has already been given.
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(Unpaid placement - FreeFind is a Search Engine Guide partner.)