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.
Froged - One click solution providing easy-to-use marketing, sales and support services to turn website visitors into happy customers.
Truepush - Unleash limitless possibilities with Truepush and save up to $600 monthly. Free up to 10K Subscribers on all features.
Keep Your Friends Close - A free e-book about maximizing Customer Lifetime Value
PushCrew - Push Notifications for Websites
Intercom on Customer Engagement - A book on how to create messages that drive engagement