OpenFisca is free software made available under the AGPL license. This means that you are free to use, install and modify it, and that you have to contribute your changes back to the community. This is the only way a contributive digital common can be sustainable, so we are very happy that you take part in this shared effort!
If you provide results based on OpenFisca usage, crediting the project would be very welcome in order to increase its visibility and to increase its contributor base. More people means more maintenance and more upgrades!
The following HTML snippet can be used to credit OpenFisca in your articles and publications:
<a href="https://openfisca.org" target="_blank" rel="noopener">
Computed by <img alt="OpenFisca" src="https://openfisca.org/img/logo-openfisca.svg" height="24" />.
</a>
<a href="https://openfisca.org" target="_blank" rel="noopener">
Calculé par <img alt="OpenFisca" src="https://openfisca.org/img/logo-openfisca.svg" height="24" />.
</a>
If you provide a service that uses OpenFisca, either bundled in a program or serving it over the network, be it directly or wrapped through another API layer, you have to credit OpenFisca, give a link to its source code and license.
The following HTML snippet can be used to credit OpenFisca, for example in your footer or “about” page. Please make sure to update the destination of the source code link if you use a modified version!
<span>Computations powered by
<a href="https://openfisca.org" target="_blank" rel="noopener"><img alt="OpenFisca" src="https://openfisca.org/img/logo-openfisca.svg" height="24" /></a>,
whose <a href="https://github.com/openfisca/openfisca-core">source code</a>
is used under an <a href="https://choosealicense.com/licenses/agpl-3.0/" target="_blank" rel="noopener">AGPL</a> license.
</span>
<span>Calculs fournis par
<a href="https://openfisca.org" target="_blank" rel="noopener"><img alt="OpenFisca" src="https://openfisca.org/img/logo-openfisca.svg" height="24" /></a>,
dont le <a href="https://github.com/openfisca/openfisca-core">code source</a>
est utilisé sous licence <a href="https://choosealicense.com/licenses/agpl-3.0/" target="_blank" rel="noopener">AGPL</a>.
</span>
If you modify or extend OpenFisca, you are legally required to make those changes available to the community. The easiest way to do it is to publish your fork of the core package, and of any country package, extension or reform, on a source hosting platform such as GitHub, and to notify the core team of this publication.
You can read this analysis to get more insight on what you can and can’t do with APGL licensed software.
If you see opportunities in developping services/business/tools on top of OpenFisca but are concerned with the AGPL3 license implications, please open an issue to have a public discussion on the topic.