Dropbox - Online Sync and File Sharing
PushCrew - Push Notifications for Websites
Syncthing - Syncthing replaces proprietary sync and cloud services with something open, trustworthy and...
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.
ownCloud - ownCloud is an open source project enabling businesses to host their own cloud storage while maintaining regulatory and compliance needs.
iZooto - Engage your mobile and desktop web users with intelligent web push notifications.