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flict / FOSS License Compatibility Tool


FOSS License Compatibility Tool (flict) is a Free and Open Source Software tool to verify license compatibility for a package and its dependencies. You can use the tool to automate license compatibility verification in your compliance work flow.

flict can:

  • verify license compatibility for license expression and a package with dependencies

  • suggest candidate outbound licenses

  • simplify license expressions

  • display, in misc format, compatibilities between licenses

  • check outbound licenses against a policy (policy as supplied by the user)

flict supports:

  • 104 licenses (flict -of text list)

  • normalizing common non SPDX ways to write licenses (e.g GPLv2 -> GPL-2.0-only) via foss-licenses

  • adding your own licenses (and compatibilities), see "Extending the license db" in SETTINGS

  • specifying licenses that are not allowed, see "Denied licenses" in SETTINGS

  • specifying license preference in case of a choice (e.g. "MIT OR FTL"), see "Preferred licenses" in SETTINGS


Check out our EXAMPLES

Extensible and tweakable

flict does not come with any knowledge about licenses and their compatibilities or license prioritiy prefeerences. These things are specified outside the tool, using JSON and CSV files. By default flict has files defining licenses and compatibilities which probably gets most of our users going. Having licenses and compatibilities (and even more stuff) defined outside the tool makes it easy to extend the tool with new licenses etc without modifying the code.

Read more in SETTINGS

Supported licenses

License matrix

To check compatibility between two licenses flict is using osadl-matrix which is using OSADL's matrix.json as found in Open Source License Checklists


Look at our INSTALLATION page.

Docker image

Flict is included in the docker image Compliance Tools which is easily managed by Compliance Tool Collection

Exit code and reports

flict outputs a report as well as an exit code.

Exit code

0 - success

5 - missing arguments

10 - invalid project file

11 - invalid expression

12 - file not found

Compatibility verification report

A report of the component's compatibility with suggested outbound licenses is created. By default a short text report is created, but flict can provide a report in a couple of formats.

Report formats


Default. Available for all commands.


With markdown output you can use pandoc to create output in other formats (e.g. html, pdf). Partially supported.


Partially supported.

User specific configuration

You can create a user specific configuration for the tool that defines a few default parameters to your choices. Either create a json file at ~/.flict.cfg or at a path defined by environment variable FLICT_USERCONFIG.

key sets CLI option
license_matrix-file -lmf --license-matrix-file
licenses_denied_file -ldf --licenses-denied-file
licenses_denied_file -ldf --licenses-denied-file
alias-file -af --alias-file
output-format -of --output-format

Example user configuration

    "license_matrix-file": "/my/very/own/osadl-matrix.csv",
    "output-format": "text"

Reporting bugs

File a ticket at

Contribute to the project


License of flict

flict is released under GPLv3 (