SuprSend - Single Notification API for Every Channel (SMS, Slack, Whatsapp, Email, SMS, Push, App Inbox)
Noticeable - The most intuitive platform to manage product updates and company announcements.
MagicBell - Your app needs a notification inbox – with real-time sync, web & mobile push, and a UI that matches your brand.
Slack with your Users - Speak to your app's users entirely within Slack
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.
GetChat.App - Add WhatsApp chat to your website for free