Alan Shreve built ngrok, an HTTP tunneling service used by tens of thousands of developers, as he learned Go and wanted to create a tool to make web development easier. He realized that making HTTP requests was expensive and created ngrok to avoid those costs, allowing him to easily replay HTTP requests without having to press dial again. With the help of the Go community, Alan built ngrok, which has become an essential tool for developers, and his story highlights the importance of collaboration and community in software development.