Open source licenses in closed source projects

Hello fellow linux-users,

I personally am pretty confident and happy with open source software and use it whenever wherever I can.

A thing I’m currently wondering about, is the definition of GPL, AGPL and the term “copyleft”.

Could anyone (most favorably with a software development background) elaborate a bit about what it would mean to use AGPL v3 licensed libraries without adjustments to it’s source inside a closed source application?

Does it in fact mean, that the previously closed source application which uses an AGPL licensed library to provide a certain functionality in a small part of the source code will need to be open sourced when it’s released?

Or does it on the other hand in terms of “copyleft” mean, that only derivative work which is based on the source code of the AGPL licensed library will have to be open sourced?

Thanks in advance for enlightening me a bit in this regard.


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“Copyleft” basically means, it’s the opposite of “Copyright”.

Instead of keeping knowledge to yourself, you are encouraged to share it, so other can improve on it and extend the knowledge. It’s a circle of becoming better & better.

Whereas, when you keep something to yourself, you only can make it as smart as yourself or your company. So, not very smart. Because if you share it with everyone, everyone can contribute to it with their unique smartness, making it the better product.

Licences, like any truly GPL-like one, are about sharing and doing whatever you want with it. However, you may not exploit the freedom by limiting it. The only thing you are forced to do by the license is to keep the freedom and never take it away. This is basically what the GPL is saying.

Do whatever you want, but do not limit its freedom.

For example, the biggest freedom limitation in that regard would be, stealing the product meant for sharing and evolving to close it off and work on it with your limited resource, like, for example, just your own company, instead of everyone in the world.

The disadvantages of the AGPL are: Puts some teams off open-source packages as it forces all other code to become GPLed software. Some view it as excessive as any module in any dependent package that uses AGPL makes all other software subject to similar restrictions.

Due to that, the AGPL licences are often misused by companies, to make their core app open source, without other companies stealing it, as they would need to open source everything, when they would start using this core app under an AGPL-like licence.

I ain’t a lawyer and this is not financial advice, but I assume that this the case, yes.

That’s the case with GPL.


Wow, pretty comprehensive answer after just an hour I posted the question. :+1:

Thanks for your information and guidance by the provided links.

I’ll have a deeper look, but think I got a good first grasp of what it would mean to use AGPL-licensed third-party-software.

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