zuul-ngrok is a plugin for Zuul that enables using ngrok as a tunneling service to expose tests to the internet, which is particularly useful for running tests in environments like SauceLabs. It allows users to configure ngrok options, such as authentication tokens, subdomains, and protocols, directly in the `.zuul.yml` file. This project is designed for developers using Zuul for testing who need to run tests on external services or browsers.