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European Public Licence

As of version 2.x, we use the European Public Licence (The EUPL) for our primary project, our Discord bot framework.

Previous versions were licenced under the Mozilla Public Licence. You can find the source code for the last version of that project we licenced under the MPL in the v1 branch on GitHub.

We understand that software licencing can be confusing at the best of times. This is especially true when dealing with an uncommon or poorly-documented software licence — such as the EUPL.

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While we've tried to provide as much information as we can under our understanding of the EUPL, we aren't lawyers and this document doesn't constitute legal advice.

The EUPL text always takes priority over anyone's opinions, but we hope to clarify a few things by explaining how we interpret it.

About the Licence​

According to the European Commission, the EUPL is a copyleft licence, designed to be compatible with other copyleft licences when combined downstream into a larger work — and to be interoperable, according to European copyright law. It includes multiple translated versions (which hold equal legal value), covers distribution through a network (such as Discord), and includes a Developer Certificate of Origin.

What this ultimately means is that the EUPL functions like a more compatible and interoperable AGPL, including a network use clause, but also a linking exception. Instead of containing its own definition for what a derivative work is, it defers to European copyright law — specifically, Directive 91/250/EEC, re-codified 2009/24/EC.

It additionally defers to the copyright law of the EU member state where the project owner resides, or the one defined within the files' licence headers, if provided. In our case, this means that the applicable law applies to the Republic of Ireland, specifically within Dublin's jurisdiction for legal challenges.

Our Mindset​

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This section encompasses our own opinions. We're sure some people will disagree with us, but we're firm in our beliefs — so find something else to spend your energy on other rather than trying to change our minds!

It is no secret that politics in open source software has deeply altered today's technological landscape. While we feel that many of these changes have been positive, some of them have definitely been negative.

The GNU Project has, for a long time, steered the discussion on what it means to write open-source software and what it means for software to be "free" — trying to move the needle in whatever direction Richard Stallman desires. Given that free software is inherently political, and the self-crowned leader of that political movement can't meet even basic moral standards, we wonder whether we could do better.

Additionally, the modern open-source movement has largely diverged from the original ideals of the so-called free software movement. This means we must deal with things as they are, not how Stallman claims they are or should be.

Unfortunately, we're not in a great place right now. The rise of generative AI (AKA theft-as-a-service) has laid bare companies' intentions to strip-mine our community and industry until there's nothing left of it. The open-source sustainability crisis shows that large companies take advantage of open-source projects and provide nothing in return — no code contributions, no donations, no marketing, nothing.

The open-source movement (maybe intentionally, we think) enables this, along with many of the licences that have the privilege of the "open-source licence" label.

We are no longer willing to be a source of labour for the corporate world to use without giving anything back.

The normal response to these concerns is to simply tell us to use the GPL or AGPL. However, these are "viral" licences, requiring any public downstream dependent project to use the same licence, or a similar one.

To maintain downstream developer freedom, we decided against picking any viral licences. The only remaining GNU licence was the LGPL, which we felt didn't provide adequate protection for our projects.

Ultimately, the only suitable licence we could find was the EUPL. It guarantees that any downstream project or product must provide an attribution notice at minimum, assuming it is available to the public in some way. If anyone modifies one of our EUPL-licenced projects, and they make that modification available to the public in some way, the EUPL guarantees that they must make those modifications publicly accessible as well.

We hope that this will help to direct a handful of new users to our projects and allow us to incorporate any changes that would be helpful to our users, but the developer didn't contribute back.

Our Interpretation​

While our interpretation cannot be treated as legal advice, we feel it may be helpful to explain what we expect from our users.

  • The EUPL is a copyleft licence. This means you can freely copy and distribute Kord Extensions, as long as you follow the conditions in the licence text.

  • European law allows for the reproduction of "interfaces" without the permission of the rights-holders. This means that the copying of names from an API (such as what happens with linking) doesn't require that your project be licenced under the EUPL, or indeed any specific licence.

    This was particularly important to us, as we didn't want to force any specific licence onto bots, modules, plugins, or other related projects using Kord Extensions, and we wanted to allow for use by proprietary and commercial projects.

  • The EUPL includes a "network use" clause — it treats distribution and communication as equal, and communications of functionality over a network (such as Discord) require you to follow all the distribution requirements.

    Due to the linking exception described above, this doesn't apply to your bots' code, but it does apply to Kord Extensions itself, as explained below.

  • The EUPL states that all distributions or communications of a work must include all copyright, patent or trademark notices that refer to the licence and to the disclaimer of warranties. In our case, we simply ask for a mention of Kord Extensions, and a link back to our site, which the bundled /about command provides by default.

    The GitHub Discussion used to collect contributors' permission to re-licence under the EUPL also asked for permission to provide alternative licences pending an application process. We haven't created a process for this yet (as nobody has asked for an alternative licence), but the option remains open if this arrangement doesn't work for your project.

Combining​

When creating a combined work (such as a fat JAR containing your bot along with Kord Extensions) for public distribution or use, the EUPL version 1.2 defines several compatible downstream licences you may use.

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It is worth pointing out that this doesn't mean that you can re-licence Kord Extensions.

Instead, this means that you can provide a larger combined work including Kord Extensions under one of the compatible licences, as long as you follow the terms set out by the licence applied to Kord Extensions.

Failure to follow the Kord Extensions licence means you lose the right to distribute it!

  • GNU licences:

    • AGPL version 3
    • GPL version 2 or 3
    • LGPL version 2.1 or 3.0

  • Other Software licences:

    • Cea Cnrs Inria Logiciel Libre licence (CeCILL) version 2.0 or 2.1
    • Eclipse Public licence (EPL) version 1.0
    • European Union Public Licence (EUPL) version 1.1 or 1.2
    • Mozilla Public Licence (MPL) version 2
    • Open Software licence (OSL) version 2.1 or 3.0
    • Québec Free and Open-Source Licence (LiLiQ-R or LiLiQ-R+)

Your Work​

While the EUPL applies specifically to Kord Extensions above, we felt it was worth explaining the specifics of what it means for your projects.

Linking​

While no European court has tested the legal definition for linking, we understand it to mean the copying of names and API definitions from another project yours is compiled against, without actually distributing the project you're linking to.

Under European law, this doesn't require rights-holder permission, and it doesn't impact how you must distribute or licence your project.

Ultimately, this means that you're welcome to keep your bots and plugins closed-source or open-source them under any licence you wish, as long as they don't include a distribution of Kord Extensions.

Modifying​

If you modify Kord Extensions and use it in a bot or other distribution or communication, you must provide access to the source code of your modified version and state what changes you've made to it. Additionally, you are not allowed to remove the references to Kord Extensions in the /about command (including removing the command or extension), unless you reproduce those references in another public command with equal visibility.

The simplest way to do provide your source code and list of changes is to fork the project on GitHub, and this is what we'd prefer. However, you may also provide a link and state your changes in your bot's /about command.

We believe that Kord Extensions is at its best when it accounts for as many project types as possible, and we always prefer contributions that make Kord Extensions more suitable, rather than multiple diverging forks.

As all developers maintaining Kord Extensions forks must licence them under the EUPL version 1.2, we may inspect forks and integrate their changes with Kord Extensions or make our own changes inspired by the forks, without notice. However, we will do our best to credit you by listing you as an additional author in each relevant commit.

Combining​

While we don't see any realistic reason to create a public combined work, we want to ensure that we also account for that project type.

We understand a combined work to be a larger work (such as a bot) that itself includes a distribution of Kord Extensions — regardless of whether that distribution is modified — in either source code, compiled or binary format. Examples of combined works include:

  • Distributions such as those created by the Gradle distribution plugin or the Gradle Shadow plugin.
  • Containers, including Docker containers, regardless of how a developer may intend to deploy them.
  • A distribution of your project's source code that contains the Kord Extensions source code in-tree.

Where you make a combined work available to the public, you must distribute it under one of the EUPL's compatible downstream licences. If you aren't distributing Kord Extensions' source code along with your project's, then this doesn't mean you must licence your project's code this way, or that your project must be open-source. However, you must distribute your project in a way that follows the terms of the collective licence you're using.

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It is worth pointing out that this doesn't mean that you can re-licence Kord Extensions.

Failure to follow the Kord Extensions licence means you lose the right to distribute it!

We recommend against distributing Kord Extensions in source code format, and you should dynamically link to it whenever possible, ideally using the KordEx Gradle plugin.

Running​

Under the terms of the EUPL, a "distribution" or "communication" are treated as equal, and the same terms apply to both. To quote the EUPL directly:

‘Distribution’ or ‘Communication’: any act of selling, giving, lending, renting, distributing, communicating, transmitting, or otherwise making available, online or offline, copies of the Work or providing access to its essential functionalities at the disposal of any other natural or legal person.

This means that running a Discord bot using Kord Extensions counts as a "distribution" or "communication", as you are exposing its functionality to users on Discord. As a result, you will need to follow the terms of the EUPL, even if your project's source code is not publicly available, and you're not using a modified version of Kord Extensions. This is true even if it is a small bot for a private server, as Discord ultimately decides who has access to your bot, rather than you having direct control over it.

To make this easier, Kord Extensions provides the /about command, which includes a small footer mentioning Kord Extensions, linking to its website, and mentioning its licence. You should configure this command with your bot's information, otherwise it'll look strange and a little barren.

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To remain compliant with the terms of the EUPL, your bot must have an easily accessible notice including the following:

  • A link to the Kord Extensions website or GitHub repository.
  • A note that your bot uses Kord Extensions and that it is licenced under the EUPL version 1.2.

For this reason, we strongly recommend that you don't attempt to remove the /about command from your bots or any modified version of Kord Extensions in any way.

Questions and Concerns​

If you have any questions regarding Kord Extensions and its licencing, please feel free to contact us via any of our community spaces.

If you have any questions about the EUPL's wording or how to use it, the European Commission provides a contact form you can use to ask legal questions.