Convert JavaCC grammar files (JJ) online for free
The converter easily converts your JJ grammar files to various formats - free and online. No JavaCC or or other Developer software needed.
To convert other file formats to the "Parser Grammar File" file type, you need software like JavaCC or a similar tool.
The .jj file extension is most frequently associated with JavaCC (Java Compiler Compiler), a parser generator for the Java programming language. These files contain the formal grammar specifications used to generate a parser. While they are essentially plain text, the proprietary extension often confuses standard text editors, and the file itself is useless without being processed by the JavaCC build tool. Users often need to convert these to TXT to view them on mobile devices or PDF for documentation and archiving purposes without setting up a development environment. For developers, the goal is typically compiling them into JAVA source code.
A secondary, less common use of the .jj extension is found in the legacy JJ Race app, which uses the extension for image assets. In this context, the file is often just a renamed JPG or BMP that the operating system refuses to preview due to the obscure extension. Users encountering these files typically need to convert them to standard JPG, PNG, or WebP formats to make them viewable in standard photo galleries or web browsers. Our tool automatically detects whether your file is text-based grammar or a binary image and handles the conversion accordingly.
Use Convert.Guru to open and convert your JJ file.
Users also converted JFIF, PP, BMS and ERL files.
If you want to convert JJ file to , you can use JavaCC or similar software from the "Parser Grammar Definition" category. In the File menu, look for Save As… or Export….
To convert files to JJ, try JavaCC or another comparable tool in the "Parser Grammar Definition" category.
The history of Convert.Guru began over 25 years ago in California with Tom Simondi’s file-format database. A former contributor to Space Shuttle development and a software pioneer of the 1980s, Simondi established a trusted resource for file type analysis that was even referenced by Microsoft Windows XP. Today, we use modern technology to process and convert thousands of file formats while continually improving our JJ converter.