How can I make load testing of Telegram (of FB Messenger) Chatbot? Is there any online/offline tools like load testing in Microsoft Bot Framework?
I know about tools such as Tsung, but how can I use it when chatbot deployed on Heroku?
Tsung is hard, I recommend to use Jmeter since you just need to test your single HTTP API endpoint.
Your bot has a webhook entry point - this is a single HTTP API request. So you just need to push some load into it.
You can try to emulate different HTTP requests with different body data (Telegram messages, statuses, other data.) and then start with 1, 5, 10 requests per second. Jmeter provides all this stuff. And then monitor your Heroku app for errors in logs etc.