ngrok is a tool that securely exposes a local development server to the internet. This allows developers to test webhooks and other integrations that require a publicly accessible URL without deploying their code to a public server. With ngrok, you can create a secure tunnel to your local machine, which is assigned a unique URL that can be accessed from anywhere. This allows you to test and debug your code without having to deploy it to a public server.
Starting a server is simple: run ngrok http <port-number> on your command line.