Is there a messenger like telegram with an open API for C#?

Question

API

Whatever messenger is needed is normal in order to receive notifications from a self-made service, that is, one for which a protocol or API for sending messages is open, so far I could not find one that would have a normal API, with working examples in C #.
Solution:
Using Slack - neurowareblog.blogspot.com/2015/08/c-send-message-...

Answer 1

What's wrong with Slack? Convenient messenger, chic API, there is a free plan.

Answer 2

Jaber look.

Answer 3

lmgtfy.com/?q=telegram+c%23