In my understanding, GPL is a copyleft license where your code can only be used in open-source projects (vs permissive licenses where your code can be used in closed-source projects).

Based on a few quick searches and my general understanding, it seems that AGPL is a more restrictive license where closed-source projects can’t depend on your code at all (?) and LGPL is a more permissive license where your code can be used in closed-source projects (?).

edit: After a bit more searching, I found that LGPL is still a copyleft license but a “weak” one. It looks like LGPL code used in other projects, if in their original form, can be closed-source but must be open-source if there are any changes. What constitutes as a change? Do ports count? How about updating syntax, like Python 2 to 3?

Also, it seems that AGPL might be almost the same as GPL (both are “strong” copyleft licenses) where AGPL just has a clause for source code sharing when it is shared over a network. In that case, why use GPL over AGPL, and vice versa? There seems to be many projects using GPL, so what is the downside to AGPL? Is the network sharing thing a bad restriction for some people, and why?

(back to original post from here)

I could be wrong on some or, more likely, all of those points. I also have a few questions. What is the difference between GPLv2 and GPLv3? If LGPL is more permissive, what are its differences compared to a license like MIT? Why would you go for one or another? And for AGPL, why would you prefer one over another? Is it simply how much (or really, how little) you want your code to be used in closed-sourced projects? And how do all these licenses interact with each other? Can you use GPL code in AGPL projects, and vice versa? What about LGPL code, is that too permissive for GPL or AGPL or can it be used in those projects?

  • thatonecoder@lemmy.ca
    2·
    4 days ago

    @grue@lemmy.world 's explanation is spot on. However, just to practice summaries, I’ll write anyway.

    Here are a few terms I’ll use:

    • Project A
    • Project B

    The GPL family of licenses are all copyleft. This means that any code used from Project A in Project B, for instance, makes the latter have the same license, along with not being able to make either Project A or B proprietary*. Furthermore, with copyleft licensed software, you have to give the corresponding source code, along with the compiled binary.

    The difference between the v2 and v3 versions of GPL is that, with the former, Tivoization was possible. Tivoization makes you only able to use the “official” version of the software, rendering it proprietary. Now, here is the comparison between the GPL variants:

    • GPL: The first of the kind, not much to say here.
    • LGPL: It allows you to link (as in libraries) code from Project A to B, without making Project B use the license, too
    • AGPL: You’ve certainly heard of SaaS, which allows you to serve websites licensed under the GPL, for example, without giving the corresponding source code. The AGPL solves this.

    *That is, if there are more contributors to Project A that have not given up their authorship. Also, the version of Project A that used the GPLv3 before can still be used under the same license.