License audit tooling for Fedora packages

This page describes some of the tools that have been used to audit licensing of packages in Fedora Linux.

Packaging tools

The following tools are specifically designed for use with Fedora Linux packages. They use the Fedora License Data as a source of data on valid licenses.


rpmlint is the standard tool used for evaluating Fedora Linux packages for well-known issues for packagers to fix. In the context of licensing, rpmlint evaluates the License: field in the spec file and ensures the values conform to the known set of allowed licenses.

This is packaged in Fedora Linux as rpmlint.


rpminspect is the tool used to evaluate Fedora Linux packages for policy compliance, differences as compared to previous builds, and common packaging errors as they are built in the Fedora Build System. In the context of licensing, rpminspect evaluates the License: field in RPMs and ensures the values conform to the known set of allowed licenses.

This is packaged in Fedora Linux as rpminspect. To use it, you need both rpminspect and rpminspect-data-fedora.


license-validate validates license strings. It can validate the Callaway format and SPDX expressions. Without the -v flag, the command does not print anything and will return a non-zero exit code when the license expression is invalid.

$ license-validate -v --old 'GPLv2 or MIT' Approved license $ license-validate -v 'GPL-2.0-only OR MIT' Approved license ---

This is packaged in Fedora Linux as license-validate.

License matching to SPDX License List for a specific license text

The SPDX project has guidance on various tools and methods to determine if a given license text matches a license already on the SPDX License List. See license match

If you identify a license or exception text as a match to an SPDX identifier, you can then use the SPDX identifier to search in the allowed and not-allowed license lists for Fedora.

License scanning tools for source code

The following tools have been used by Fedora Project contributors to detect licenses in the source code of current and proposed Fedora Linux packages. All of these tools are distribution-agnostic.


Licensecheck is a tool used to analyze the licensing of source files. This tool is principally used in the Fedora context for the initial package review for packages proposed for inclusion in Fedora Linux. Licensecheck is run automatically as part of FedoraReview.

By default, licensecheck provides license reports with full license names, but can be used to produce output using any number of license identifier schemes.

This is packaged in Fedora Linux as licensecheck.


Askalono, packaged in Fedora as askalono-cli, is a simple license scanning tool written in Rust. It is most useful for quick analysis of packages coming out of ecosystems featuring projects known to have (1) highly standardized approaches to layout of license information (it specifically looks only for files that are named LICENSE or COPYING or some obvious variant on those), (2) generally simple license makeup, and (3) cultural preferences for a highly limited set of licenses (for example, Rust crates that don’t bundle legacy C code, Go modules, or Node.js npm packages).

Askalono has some significant shortcomings. It can’t recognize or understand: (1) license notices/license texts that are comments in source files, (2) license notices/license texts in README files, (3) license files that contain multiple license texts (or it will only recognize the first of them), and (4) nonstandard/archaic/legacy licenses (which covers most of the licenses being reviewed in issues in fedora-license-data)


FOSSology is a license compliance software system and tooklit that includes license scanning. It can be run locally and also can be set up as a hosted service. The FOSSology website provides information on using a test instance hosted by the OSU Open Source Lab.

FOSSology is good for scanning an entire package for licenses (or texts that look like licenses). Files can be viewed easily in the FOSSology interface. FOSSology has the ability to remember past license inspection decisions.

Some tips on using FOSSology: * In Options: #5 - check "Ignore SCM files" #7 - check Monk, Nomos, Ojo License Analysis and Package Analysis ** #8 - check first two options re: "Scanners matches…​" * Go to License Browswer view. Look for license matches that are suspicious or unexpected, such as things that are not an SPDX identifier or ambiguous. You can then view the files with those matches and inspect what was found to determine if there is a license that needs to be recorded or if it is a false match. Basic Workflow has some helpful information.

FOSSology is not packaged in Fedora.

ScanCode toolkit

ScanCode toolkit is a command-line Python tool and library for detecting licenses, copyrights, package metadata and related information in source and binary code. ScanCode detects licenses by doing a diff against a database of 37,000 license texts and notices.

ScanCode output includes SPDX documentat and a variety of other formats including JSON, YAML, HTML, CSV, CycloneDX and Debian machine readable copyright files.

ScanCode reports detected license information using valid SPDX license expressions (and also ScanCode’s own extended list of license keys that includes licenses that are not included in the SPDX License List). It applies the SPDX matching guidelines when possible and provides detailed information on the matched texts and detected licenses.

ScanCode toolkit is also embedded in other tools such as FOSSology, tern, ORT, and FOSSLight.

ScanCode toolkit packaging in Fedora is in progress. It can be installed using pip or an app tarball.

The recommended way of running ScanCode is: scancode --license --html output.html --license-references -n$(nproc --all) is a web application to run ScanCode toolkit pipelines on multiple projects. A pipeline is a script to organize the code analysis of large codebases, binaries, containers (or single packages) with optional code matching against an index of pre-existing FOSS code. is useful for scanning an entire package for licenses notices, license texts and "license clues". Files can be viewed easily in the interface. See Documentation to get started. is not yet packaged in Fedora. It can be installed using containers and podman.


Trivy is more robust than Askalono or Licensecheck but less verbose than ScanCode. Upstream provides static RPM packages.

You can run the check with command: trivy fs --scanners license --license-full .

More details about Trivy license scanning.