While JavaScript has been the language for web applications, JavaScript web applications are often vulnerable to type-related errors and security attacks. To lessen the problem, researchers have developed various analysis techniques in different analyzers, but such analyzers are not especially aimed for ease of use by analysis developers. SAFE, a scalable analysis framework for ECMAScript, is especially designed as a playground for advanced research in JavaScript web applications. SAFE is light-weight, which supports pluggability, extensibility, and debuggability. In this tutorial, we walk the attendees through this process. We start with a technical overview of the SAFE framework and its support for analysis of JavaScript web applications. Then, we present two concrete use cases of SAFE: a taint analysis of web applications and a cross-project big code analysis.