Installation

CongoCC is distributed as a single executable JAR file with no other runtime dependencies. Installing it amounts to downloading that JAR — or building it from source — and making sure you have a suitable Java runtime.

Requirements

  • Java 17 or later to run CongoCC. The tool ships as Java bytecode no matter which language you generate parsers in.

  • A toolchain for your target language, needed only to compile and run the generated parser: a JDK for Java (the default), CPython for Python, the .NET SDK for C#, or a Rust toolchain for Rust. See the Target Language Guide for the per-language details.

Note

You do not need the target-language toolchain in order to generate a parser — only to compile and run it. CongoCC itself only requires Java 17+.

Getting the JAR

Download the latest build:

$ curl -L -O https://parsers.org/download/congocc.jar

Verify it works by invoking it with no arguments. CongoCC prints a banner followed by its usage message:

$ java -jar congocc.jar

Usage:
    java -jar congocc.jar grammarfile

The following command-line flags are available:
 -d <directory>    Specify the directory (absolute or relative to the
                   grammarfile location) to place generated files
 -lang <language>  Specify the language to generate code in (the default is 'java')
                     (valid choices are currently 'java', 'python', 'csharp' and 'rust')
 -n                Suppress the check for a newer version
 -p                Define one or more comma-separated (no spaces) symbols to
                   pass to the preprocessor.
 -q                Quieter output

The first banner line reports the build date of your JAR, which is handy for checking whether you are running the most recent version:

CongoCC Parser Generator (congocc.jar built ... on 2026-06-23)

Tip

By default CongoCC checks online for a newer release each time it runs. Pass -n to suppress that check — useful when working offline or in a continuous-integration job.

The full command-line reference, including the syntax converter for legacy JavaCC grammars, is in Invocation.

Building from source

If you want the bleeding edge, or intend to work on CongoCC itself, build the JAR from source. You will need Git, a JDK 17+, and Apache Ant:

$ git clone https://github.com/congo-cc/congo-parser-generator.git
$ cd congo-parser-generator
$ ant

The default Ant target builds the project and produces congocc.jar in the repository root. To build and run the test suite instead, use:

$ ant test

See the top-level build.xml file for all possible build targets.

Optionally Building Rust Examples

Rust examples and test code are not built by default. If the Rust toolchain is available, you can build all artifacts from scratch, including Rust artifacts, by using:

$ ant clean -Drust.enabled=true
$ ant test -Drust.enabled=true

See Rust Target Language Guide for more information about Rust support.

Editor support

A CongoCC grammar is an ordinary UTF-8 text file — conventionally given a .ccc extension — so any text editor will do. The source repository ships a workspace.code-workspace file for Visual Studio Code, and the complete grammars under its examples/ directory (JSON, Lua, Python, Java, C#, and more) are worth opening alongside your own work as references.

Next steps

With the JAR in hand, continue to Your First Grammar to write, generate, and run your first parser.