Blockbutler - Real-time transaction notifications for the blockchain
CryptoNotify - Receive transaction notifications of any BTC or ETH address
Pushover - Real-time notifications on your Android, iPhone, iPad, and Desktop
Notif.me SDK - A Node.js lib to send all your transactional notifications
Pusher Beams - Send push notifications programmatically at scale
Kids App Hunt - Let's talk about the best apps for kids