Our tool can help you find the backlinks that are pointing to 404 pages of your website. To do that:
go to Your Links dashboard and click New Filter:
Select "Destination page with" in the drop-down menu and then select "is Page with errors/redirects":
Also, apply filters so that you limit your search to high quality links (after all, you don't want to spend time trying to fix undesirable spammy links).
Then, look for links that show a 404 on the landing page:
For each of those landing pages that show 404, you have to identify whether:
the link was incorrectly written by the site linking to you (and you have a separate, correct link that they should put instead)
the link is broken on your site
For the first situation, you can contact the webmasters manually and ask them to fix the link. Our tool just reports your SEO progress and problems, but the outreach process will have to be manually done.
For the second situation, you or your web developer should fix the problem as soon as possible. It's lost link juice, so fixing it will improve your rankings. It should be a very simple fix for any developer.