How to find broken-links for link building ?
You can Find Many broken links Easily on Google but The Best recommendation is to go for the wiki broken links. It helps Alot
are you trying to find links that are broken within your site? You can use http://home.snafu.de/tilman/xenulink.html its a old program but works great
Xenu Link Sleuth is the best free tool to find the broken links.More info you can check this link :- http://www.brokenlinkcheck.com/
There are many tools for checking the broken links. You can try brokenlinkcheck or deadlinkchecker
A broken link is a dead link on a web page that no longer works because the website is un-expecting one or more of the reasons below. An improper URL entered for the link by the website owner. The destination website removed the linked web page.
There are many tools to find broken links such as brokenlinkchecker brokenlinkfinder etc.
Why is it good for SEO ?
There are many tools for broken link checker tool that is free tool.http://rnd.net.in/web-design-company-hyderabad.php