We visited brokenlinkcheck.com, we tested tomydna.com and we compared it to the error reporting from sitecozy website checker.
Result from brokenlinkcheck.com
Brokenlinkcheck.com successfully found the malformated URL, an external URL that does not work and an internal URL that does not work. Two first errors returned “bad host” and the last one returned a 404
It found 3 errors.

Sitecozy broken link checker result:
The sitecozy broken link checker found 10 errors for the same website.
The SiteCozy broken link checker finds mixed content errors while brokenlinkcheck.com does not look for mixed content errors. The Sitecozy BLC returns the mixed content error when the protocol of an internal link is HTTP and when the host page is HTTPS.
If I withdraw the mixed content errors, there are still 5 errors. It looks like brokenlinkcheck.com missed two 404 not found errors returned by image URLs.