A Telegram Bot to translate simple JSON HTTP requests into Telegram push messages that you will get on your Smartphone, PC, or whatever Telegram client you have. Just like Gotify, but without an extra app.
This is especially useful for developers or sysadmins. Imagine you want some kind of reporting from your application or server, like a daily report including some statistics. You don't want to actively look it up on a website but you want to receive it in a passive fashion. Just like getting an e-mail. But come on, let's be honest. E-Mails are so 2010. And they require your little server-side script to include some SMTP library and connect to a mail server. That's too heavyweight just to get some short information. Personally, I have a Python script running on my server which gathers some statistics from log files and databases and regularly sends me a Telegram message.
If you develop those thoughts further, this could potentially replace any kind of e-mail notifications - be it the message that someone has answered to your forum post, your favorite game is now on sale at Steam, and so on. It's lightweight and easy, unlike e-mails that have way too much overhead.