Jaree

Jaree is a lightweight software application that can help you perform a single action, namely to view the contents of any JAR files.
The user interface is really simplistic, and there isn’t anything worth mentioning about it, except for the fact that it can give you details about the name, size and date of the Java-based files.
It doesn’t offer users the possibility to drag and drop the documents directly into the main window, so they should add them by using the built-in browse function.
The application displays in the main window a hierarchical structure of the JAR files, and with a simple double-click on any class you can view details about members and methods.
This tool bundles only a few options for helping you manage the JAR files, as it allows users to copy the packages, members and methods to the Clipboard. Moreover, you can also copy the internal type signatures, and this proves to be pretty useful, especially if you intend to write JNI code.
To sum things up, Jaree isn’t the most powerful tool that you can use for handling JAR files, as there aren't any configuration settings that could help you manage JAR files in a professional manner.
However, if you are a Java beginner who’s looking for an easy-to-use JAR viewer, you can rely on this tool to help you check out the contents of your files and copy the information. Jaree also runs on very low computer resources.