Telegram Bot – how to get a group chat id?

Here is the sequence that worked for me after struggling for several hours:

Assume the bot name is my_bot.

1- Add the bot to the group.
Go to the group, click on group name, click on Add members, in the searchbox search for your bot like this: @my_bot, select your bot and click add.

2- Send a dummy message to the bot.
You can use this example: /my_id @my_bot
(I tried a few messages, not all the messages work. The example above works fine. Maybe the message should start with /)

3- Go to following url: https://api.telegram.org/botXXX:YYYY/getUpdates
replace XXX:YYYY with your bot token

4- Look for “chat”:{“id”:-zzzzzzzzzz,
-zzzzzzzzzz is your chat id (with the negative sign).

5- Testing: You can test sending a message to the group with a curl:

curl -X POST "https://api.telegram.org/botXXX:YYYY/sendMessage" -d "chat_id=-zzzzzzzzzz&text=my sample text"

If you miss step 2, there would be no update for the group you are looking for. Also if there are multiple groups, you can look for the group name in the response (“title”:”group_name“).