Telegram really doesn't cease to amaze me with the amount of features it's packing and everything that is possible. Really tremendous development and engineering feat, especially at this scale. I love the app and use it constantly.
AFAIK this is the main documentation page: https://core.telegram.org/bots/api which, subjectively speaking is really hard to read, and, objectively speaking, offers no sample responses/interactivity.
This page tries to fill the gap on tutorials/how-to: https://core.telegram.org/bots but without sample code.
There are a few bots you can find on GitHub, but nothing official that I could find.
Documentation on bot limitations in channels vs. groups is also really spotty.
Trying to detect who joined a group/channel and greet them, for example, or trying to send a message on departure, is non-trivial.
There's also wrappers for many languages that will have auto-documentation on IDEs like IntelliJ and usage examples.
What I really dislike is Telegram's avoidance of E2EE. Very sketchy.
curl -X POST \ -H 'Content-Type: application/json' \ -d '{"chat_id": "123456789", "text": "This is a test from curl", "disable_notification": true}' \ https://api.telegram.org/bot$TELEGRAM_BOT_TOKEN/sendMessage
I even have a MotionEye cam send me little videos when it detects motion. Telegram is amazing for this.
And it's FAST.
Really good engineers they got over there.