Dr. Link Check - Broken link checker with malware and parked domain detection
OneSignal - Customer engagement platform used by over 1 million developers and marketers; the fastest and most reliable way to send mobile and web push notifications, in-app messages, emails, and SMS.
BrokenLinkCheck - Free Broken Link Checker / Online Dead Link Checking Tool - find bad hyperlinks
Truepush - Unleash limitless possibilities with Truepush and save up to $600 monthly. Free up to 10K Subscribers on all features.
LinkChecker - LinkChecker is a free, GPL licensed website validator.
PushCrew - Push Notifications for Websites