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Apache RAT
What it is
Apache RAT is a free tool for auditing software distributions, with a particular focus on license headers. RAT 0.18 provides a command-line client, an Ant task library, and a Maven plugin. Its options can include or exclude files, apply approved-license lists, and produce reports for missing headers or unapproved licenses. The Maven plugin can write a text report to target/rat.txt or add one to a generated site. The command-line tool can add Apache-2.0 headers and copyright notices to files not excluded by configuration. Users can add license definitions through XML; extending matchers, definition formats, reports, or interfaces requires relevant expertise. RAT identifies potential problems rather than settling them: reports need interpretation, project-specific tuning may be needed, and its heuristics can miss issues. The latest listed release is 0.18, available as binary and source archives. Building requires Java 17, and Apache Maven 3.9.13 or later is recommended. The software is licensed under Apache License, Version 2.0.
For and against
For
- Free tool focused on release license audits.
- Offers command-line, Ant, and Maven interfaces.
- Can report missing headers and unapproved licenses.
- Can add Apache-2.0 headers to eligible files.
Against
- Reports require interpretation and may need tuning.
- Heuristics can miss issues.
- Building requires Java 17.
The verdict
Apache RAT provides configurable release-audit workflows and multiple report options at no charge. Treat its results as potential findings that may need review and project-specific tuning.
Who it suits
It suits teams checking release distributions for license issues and integrating those checks into command-line, Ant, or Maven workflows. Users should be prepared to interpret and tune its reports.
Plans and prices
Apache RAT
Open-source release audit tool · latest release 0.18
Read 8 Oct 2026 · creadur.apache.org
On the record
- Caveat
- RAT relies on heuristics that may miss issues, and its reports require interpretation and may need project-specific tuning.creadur.apache.org · read 8 Oct 2026
- Configuration
- Command-line options support file inclusion and exclusion, license approval lists, and report output styles including missing-header and unapproved-license reports.creadur.apache.org · read 8 Oct 2026
- Download integrity
- The project recommends verifying downloaded release files with signatures from its main distribution directories and provides PGP signatures and SHA512 checksums.creadur.apache.org · read 8 Oct 2026
- Extensibility
- Users can add license definitions through XML, and can extend matchers, definition formats, reports, and user interfaces with the relevant expertise.creadur.apache.org · read 8 Oct 2026
- File selection
- RAT supports including and excluding files with patterns, standard collections, files of patterns, and file-size exclusions.creadur.apache.org · read 8 Oct 2026
- Header editing
- The command-line tool can add Apache-2.0 license headers and copyright notices to files that are not excluded by its configuration.creadur.apache.org · read 8 Oct 2026
- Integrity checks
- The project recommends verifying downloaded releases with signatures from its main distribution directories; it also provides PGP signatures and SHA-512 checksums.creadur.apache.org · read 8 Oct 2026
- Interfaces
- RAT 0.18 ships with a command-line client, an Ant task library, and a Maven plugin.creadur.apache.org · read 8 Oct 2026
- License
- Apache Creadur licenses its software to the public under the Apache License, Version 2.0.creadur.apache.org · read 8 Oct 2026
- License review
- RAT is a release audit tool focused on licenses and is intended to improve the accuracy and efficiency of checking releases for licenses.creadur.apache.org · read 8 Oct 2026
- Limitations
- RAT highlights possible issues, its reports require interpretation, it may need tuning, and its heuristics may miss issues.creadur.apache.org · read 8 Oct 2026
- Maven reports
- The Maven plugin can write a text report to target/rat.txt or add a report to the generated site.creadur.apache.org · read 8 Oct 2026
- Output formats
- The package includes stylesheets for missing-header reports, unapproved-license reports, plain output, and pretty-printed XML.creadur.apache.org · read 8 Oct 2026
- Primary use
- RAT is intended to improve the accuracy and efficiency of checking software releases for licenses.creadur.apache.org · read 8 Oct 2026
- Purpose
- Apache RAT audits software distributions, with a focus on license headers.creadur.apache.org · read 8 Oct 2026
- Release
- The downloads page lists Apache Creadur RAT 0.18 as the latest release and offers binary and source archives.creadur.apache.org · read 8 Oct 2026
- Runtime
- RAT requires Java 17; its documentation recommends Java 21 for generating Javadocs due to an existing JDK error.creadur.apache.org · read 8 Oct 2026
- Runtime requirements
- Building RAT requires Java 17, and the project recommends Apache Maven 3.9.13 or later.creadur.apache.org · read 8 Oct 2026
