Rand Fishkin of SEOMoz.org posted on their blog the best way to find out how many external links a web page has. It is widely known among SEO’s that of all the search engines Yahoo! returns the most complete and accurate numbers when it comes to links. Yahoo even has a tool called Site Explorer that show you have many pages of a site are indexed in Yahoo and how many links that site has. But, Rand reveals something here that you may not know. Check it out.
We’ve seen lots and lots of link search data from Yahoo!’s many sources – site explorer, web search, APIs for both of these, results from the engines they serve (see below), etc. To date, the most accurate link counts we’ve ever found are done via the search.yahoo.com URL. Once you get to the results page, surf to the last page of results available – you can also append &b=999 to the end of the URL manually. Yahoo!’s count will update to be more accurate and if the page only shows “results X through Y of Z,” you can use those numbers to get a good idea of how many truly unique links you’ve got.
There you have it. According to Rand, you can get the best results by going to http://search.yahoo.com and using the link: or linkdomain: commands to get the most accurate link counts for any url you want to research links for.