license_conflicts

license_conflicts detects software license incompatibilities between a project and its dependencies. It identifies the project's license, scans all dependency licenses using LicenseFinder, and reports any conflicts — making it easy to integrate license compliance checks into your CI/CD pipeline.

How It Works
Supported Languages
Requirements
Installation
Usage
Output
Report Formats
Supported Licenses
Exit Codes
Contributing
License

How It Works

Detects the project license from its metadata file (package.json, gemspec, pom.xml, etc.)
Scans all dependencies using LicenseFinder
Normalizes license names — SPDX identifiers, common aliases, and variant spellings are all mapped to canonical names
Checks for conflicts using a built-in compatibility matrix
Reports results to stdout and exits with an appropriate code

Supported Languages

Language	Package Manager	Metadata File
JavaScript	npm	`package.json`
JavaScript	Bower	`bower.json`
Ruby	Bundler	`*.gemspec`
Python	pip / Poetry	`setup.cfg`, `pyproject.toml`
Go	Go modules	`go.mod`
Go	Godep	`Godeps/Godeps.json`
Java	Maven	`pom.xml`

Requirements

Ruby >= 2.6.0
The package manager for your project type must be installed (e.g. npm, bundler, mvn)

Installation

gem install license_conflicts

Usage

Run inside the root directory of the project you want to analyze:

license_conflicts

To generate a detailed dependency report alongside the conflict check:

license_conflicts check --format markdown

To display the installed version:

license_conflicts version

Options

Flag	Alias	Description
`--format FORMAT`	`-f FORMAT`	Report format: `text`, `html`, `markdown`, `csv`, `xml`, `json`, `junit`

Output

Results are printed to stdout as a single comma-separated line:

{dependency_count}, {project_license}, {conflicting_licenses}, {report}

Field	Description
`dependency_count`	Number of scanned dependencies
`project_license`	Detected license of the analyzed project
`conflicting_licenses`	Semicolon-separated list of incompatible licenses found (empty if none)
`report`	Full dependency report (only present when `--format` is specified)

Examples

No conflicts found:

42, MIT, ,

Conflicts detected:

42, MIT, GPLv2;AGPL 3,

With a Markdown report:

42, MIT, GPLv2, ## Dependencies ...

Diagnostic messages and errors are written to stderr and do not affect the stdout output format.

Report Formats

When --format is provided, a full dependency report is appended to the output. Available formats:

Format	Flag value
Plain text	`text`
HTML	`html`
Markdown	`markdown`
CSV	`csv`
XML	`xml`
JSON	`json`
JUnit XML	`junit`

Supported Licenses

The following licenses are recognized in the conflict matrix:

MIT · Apache 2.0 · New BSD · Simplified BSD · GPLv2 · GPLv3 · LGPL 2.1 · LGPL 3.0 · MPL 1.1 · MPL 2.0 · CDDL 1.0 · AFL 3.0 · OSL 3.0 · AGPL 3 · AGPL 1.0 · EPL 1.0 · EPL 2.0 · ISC · Zlib · Unlicense

The normalizer recognizes SPDX identifiers and common aliases for all of the above (e.g. Apache-2.0, GPL-3.0-only, BSD-3-Clause). Unrecognized license names are passed through as-is and checked against the matrix.

Exit Codes

Code	Meaning
`0`	No license conflicts found
`1`	One or more license conflicts detected
`2`	Error during execution (license not found, unsupported license, invalid option)

Contributing

Contributions are welcome! Please follow these steps:

Fork the repository
Create a feature branch (git checkout -b feature/my-feature)
Write tests for your changes
Run the test suite (bundle exec rspec)
Open a Pull Request

Running Tests

bundle install
bundle exec rspec

License

This project is released under the MIT License.