We switched from Slack to Telegram a few months ago for our team communication at BetaList. Some of our website notifications (new signups, certain errors, etc) still were sent to Slack though through a variety of integrations.

I made a simple service that accepts webhook requests and posts them to Telegram. You can interface with the bot directly (@pushmorebot) or add it to a group to have notifications show up there.

You can use it in multiple groups and have different notifications for each.

One caveat right now is that that the webhook URL is visible to anyone in the group so be careful when using it in a public group. (If there's enough interest I'll add some privacy controls.)