The Java Formatter is an online tool that helps to format Java source code by adhering to the coding conventions and style guidelines. With this tool, you can easily ensure that your code is properly indented, the braces are correctly placed, the variable names are consistent, and the code is easy to read and understand. The Java Formatter can be used to format both single-line and multi-line code blocks, making it a handy tool for developers who need to maintain code consistency and readability in their projects.