Betatesters.io - The platform connecting mobile developers and beta testers
Dead Link Checker - Check for broken links on any website
Betafy - Where startups meet beta users!
BrokenLinkCheck - Free Broken Link Checker / Online Dead Link Checking Tool - find bad hyperlinks
Beta Family - 50,000 testers to test your app
LinkChecker - LinkChecker is a free, GPL licensed website validator.