It's a very cool tool that lets you expose a local webserver to the outside world (internet)- in short, it creates a secure tunnel on your local machine along with a public URL that you can use or give to your colleagues, friends, etc. for browsing or testing your local site. Go through this to know more about it: https://ngrok.com/docs I have used this where I wanted to expose my local running Jenkins to git for the webhook part.
A blog about my testing stories where I pen down my thoughts about test automation covering primarily Selenium, Java, Rest Assured, Karate, Maven, TestNG, Postman, newman, Jenkins, Git, Azure DevOps, etc.