Authpush is an easy, code-less way to send push notifications to your users.
We also have an API at https://github.com/authbaseco/authpush-api.
Also made by a 15y/o.
Push More is a Telegram bot that shows any webhook requests that are sent to it. It's a simple tool for developers for get notified of anything in they like in their messenger app of choice, Telegram.
Pingr alerts you when it matters, and is powered by people you choose.