ntfy is a free and open-source program that allows users to send push notifications to their iPhone from any Bash or PowerShell script. Developed by Philipp Heckel, ntfy provides a convenient way to receive notifications from various sources using simple HTTP requests.

With ntfy, users can subscribe to topics and publish messages via a straightforward HTTP API. This makes it easy to stay informed about important events and receive alerts directly on your phone. Whether it's receiving a notification when a long-running process is complete, being alerted about a failed backup, or getting an alert when someone logs into your server, ntfy has you covered.

Using ntfy is as simple as making a PUT or POST request, such as using curl on Linux or Invoke-WebRequest on PowerShell. For example, you can send a notification with the message "Your backup is done" to a specific topic by using the following command:

$ curl -d "Your backup is done" ntfy.sh/mytopic