Pushover - Real-time notifications on your Android, iPhone, iPad, and Desktop
Pusher Beams - Send push notifications programmatically at scale
Pushbullet - Pushbullet - Your devices working better together
Truepush - Unleash limitless possibilities with Truepush and save up to $600 monthly. Free up to 10K Subscribers on all features.
Gotify - a simple self-hosted server for sending and receiving messages
PushOwl - Re-engage website visitors with push notifications