Google Chat
Google Workspace
の1機能。
https://workspace.google.co.jp/intl/ja/products/chat/
API
https://developers.google.com/chat
Webhooks
https://developers.google.com/chat/how-tos/webhooks
ペイロード
https://developers.google.com/chat/reference/message-formats
Text
https://developers.google.com/chat/reference/message-formats/basic
Card
https://developers.google.com/chat/reference/message-formats/cards