Joern currently consists of the following components:

  • joern(-core) parses source code using a robust parser, creates code property graphs and finally, imports these graphs into a Neo4j graph database.
  • python-joern is a (minimal) python interface to the Joern database. It offers a variety of utility traversals (so called steps) for common operations on the code property graph (think of these are stored procedures).
  • joern-tools is a collection of command line tools employing python-joern to allow simple analysis tasks to be performed directly on the shell.

Both python-joern and joern-tools are optional, however, installing python-joern is highly recommended for easy access to the database. While it is possible to access Neo4J from many other languages, you will need to write some extra code to do so and therefore, it is currently not recommended.

System Requirements and Dependencies

Joern is a Java Application and should work on systems offering a Java virtual machine, e.g., Microsoft Windows, Mac OS X or GNU/Linux. We have tested Joern on Arch Linux as well as Mac OS X Lion. If you plan to work with large code bases such as the Linux Kernel, you should have at least 30GB of free disk space to store the database and 8GB of RAM to experience acceptable performance. In addition, the following software should be installed:

  • A Java Virtual Machine 1.7. Joern is written in Java 7 and does not build with Java 6. It has been tested with OpenJDK-7 but should also work fine with Oracle’s JVM.
  • Neo4J 2.1.5 Community Edition. The graph database Neo4J provides access to the imported code.
  • Gremlin for Neo4J 2.X. The Gremlin plugion for Neo4J 2.X allows traversals written in the programming language Gremlin to be run on the Neo4J database.

Build Dependencies. A tarball containing all necessary build-dependencies is available for download here . This contains files from the following projects.

The following sections offer a step-by-step guide to the installation of Joern, including all of its dependencies.

Building joern

Begin by downloading the latest stable version of joern at This will create the directory joern in your current working directory.

tar xfzv 0.3.1.tar.gz

Change to the directory joern-0.3.1/. Next, download build dependencies at and extract the tarball.

cd joern-0.3.1
tar xfzv lib.tar.gz

The JAR-files necessary to build joern should now be located in joern-0.3.1/lib/.

Note: If you want to build the development version, you need to download the build dependencies from .

Build the project using ant by issuing the following command.


Create symlinks (optional). The executable JAR file will be located in joern-0.3.1/bin/joern.jar. Simply place this JAR file somewhere on your disk and you are done. If you are using bash, you can optionally create the following alias in your .bashrc:

# ~/.bashrc
alias joern='java -jar $JOERN/bin/joern.jar'

where $JOERN is the directory you installed joern into.

Build additional tools (optional). Tools such as the code{argumentTainter} can be built by issuing the following command.

ant tools

Upon successfully building the code, you can start importing C/C++ code you would like to analyze. To interact with the database using python and the shell, it is also highly recommended to install python-joern and joern-tools as outlined in the following sections.

Installing python-joern

python-joern is a thin python access layer for joern and a set of utility traversals. It depends on the following python modules:

To install python-joern, first make sure python setuptools are correctly installed. On Debian/Ubuntu, issuing the following command on the shell should be sufficient.

sudo apt-get install python-setuptools python-dev

python-joern and all its dependencies can then be installed as follows:

tar xfzv 0.3.1.tar.gz
cd python-joern-0.3.1
sudo python2 install

Installing joern-tools

joern-tools is a set of shell utilities for code analysis based on joern. It is at a very early stage of development and has not been labeled for release. However, it can be installed from github.

joern-tools depends on python-joern for database communication and graphviz/pygraphviz for graph visualization. To install it, make sure graphviz is installed. On Debian/Ubuntu, the following command will install graphviz:

sudo apt-get install graphviz libgraphviz-dev

Just like python-joern, joern-tools is installed using python-setuptools as follows:

git clone
cd joern-tools
sudo python2 install

After installation, type joern-lookup to verify correct installation.