Please following this ponts that can help you how to check website's bad links?
Online Broken Link Checker
Scans webpages for bad hyperlinks
â€¢ Can analyse unlimited number of pages
â€¢ Useful for SEO optimization
â€¢ Checks both internal and external URLs and finds which are stale
â€¢ Reports dead link's location in your HTML code
â€¢ Validates websites online: the same way as how your users and Search Engines see those
â€¢ Detects "linkrot" and other problems of web site integrity
â€¢ Supports sub-domains
â€¢ Works on-line so can be used on Mac OSX, iOS, Linux, Windows, Android and any other OS
â€¢ Shows 404 errors and other unsuccessful HTTP response codes - for each dead or problematic hyperlink.