How do I find broken links this way?

I found a tool for broken links, https://www.deadlinkchecker.com/website-dead-link-checker.asp
Now it gives me this picture
404 Not Found https://grid.bidswitch.net/ link/href
404 Not Found https://adservice.google.com/ link/href
404 Not Found https://securepubads.g.doubleclick.net/ […]

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