In this lesson we’ll look at the amazing open source tool [ASTExplorer.net](https://astexplorer.net/). We’ll learn how we can use it to learn about ASTs generated by different tools. We’ll also see how it can be used to help us write plugins for ESLint, Babel, and other tools. The noted ESTree specification can be found on [GitHub](https://github.com/estree/estree).