Monika

Get notified from whatever app you want (Telegram, Slack, etc) when your website or API is down based on HTTP status code or content of the response, or when your server is slow. You can install it in as many as computers as you want wherever they are.

Monika is an open source and free synthetic monitoring command line application. The name Monika stands for "Monitoring Berkala", which means "periodic monitoring" in the Indonesian language.