What Is Rat?

Apache Rat is a release audit tool, focused on licenses.

Rat Is Used To...?

Use Rat to improve accuracy and efficiency when checking releases for licenses.

Why Develop Rat?

Reviewing releases in the Apache Incubator by hand was error-prone and time-consuming.

Rat arises from the Apache style, but is used more widely. If your release style isn't supported, talk to us.

How Do I Use Rat?

Apache Rat 0.17-SNAPSHOT ships with tooling for

• Apache Ant,
• Apache Maven and
• the command line.

Rat is extensible. If your build tool isn't supported, please contribute a patch or talk to us.

Rat aspires to be self documenting. Please contribute a patch or talk to us whenever Rat falls short.

How do I extend Rat

There are several standard ways to extend Rat.

• Add a license definition via an XML file.
• Add a new Matcher definition. Requires Java expertise.
• Add a new definition format. Requires Java expertise as well as expertise with the format.
• Write a new output report. Requires XSLT knowledge.

Who Develops Rat?

Apache Rat is part of the Apache Creadur language- and build-agnostic suite of tools for auditing and comprehending software distributions. Our community develops open source software the Apache way.

Please feel free to contribute a patch, demonstrate a bug, or just talk to us. All welcome :-)

Command Line

Quick start by

java -jar apache-rat-0.17-SNAPSHOT.jar --help

Read more here.

Apache Ant

Use the task library for Apache Ant 1.7 or later

Read more here.

Apache Maven

Use the plugin for Apache Maven 3.9.7 or later.

ATTENTION! Maven4 is based on Java 17 and thus cannot be used with RAT, that relies on Java 8.

  <plugin>
    <groupId>org.apache.rat</groupId>
    <artifactId>apache-rat-plugin</artifactId>
    <version>0.17-SNAPSHOT</version>
  </plugin>

Read more here.

Styling output

Rat allows you to style the output as you see fit. Three stylesheets are included in the rat package.

• plain-rat - The default stylesheet.
• unapproved-licenses - Lists only the files with unapproved licenses.
• missing-headers - List only files that are missing headers.

These stylesheets can be specified using options in the command line, Maven or Ant clients.

In addition, new stylesheets may be developed and applied to create new reports.