(Posted this on Reddit already, but I thought it might be interesting
This little gem I made uses the Telegram Bot API to easily send
notifications to your users via Telegram. As soon as a user starts your
(via a link in your app), they are stored in the database, giving you
ability to send notifications at any time.
For more information (including a demo app!), check out the GitHub page
https://github.com/ppati000/tele_notify. Also, for any questions, tips
other thoughts, feel free to contact me on Twiiter