Show HN: Scan your blog for broken outgoing links (link-sweeper.herokuapp.com)

I built this small proof-of-concept interface that lets you scan a URL or the pages in a .XML sitemap for broken outgoing links. I use this to find issues with links in my own blog and I'm wondering if this is useful for others!

I also have some cases of false positives showing up and I'd be interested in knowing if you have suggestions to better handle those cases.