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.
Mailshake - Mailshake lets you build your professional network through a smart and intuitive approach to cold emailing.
PushBots - Light SDK for mobile push notifications
Instantly - Build your own infinitely scalable cold email outreach system with Instantly.
ZoPush - Personalized Browser Push Notifications for Web and Mobile.
Snov.io - More leads. More sales. More revenue.