Best GPL-2.0 Licensed Open Source Repositories

The GNU General Public License version 2 is a strong copyleft license: you can run, study, modify, and redistribute the software freely, but any distributed version, whether unmodified or changed, must remain under GPL-2.0 and come with its complete source code. If you build a program that statically links against GPL-2.0 code or otherwise forms a combined work with it, the common interpretation is that the whole result needs to be distributed under GPL-2.0 terms as well. This is what makes GPL-2.0 'viral' in the sense that its terms tend to propagate to derivative works, in contrast to permissive licenses like MIT or Apache-2.0.

GPL-2.0 predates GPL-3.0 and lacks some of its successor's additions, such as explicit patent grant language and protections against 'tivoization', where hardware restricts users from running modified versions of software they legally have the source for. Some projects stay on GPL-2.0 specifically because they want to avoid GPL-3.0's added obligations, or because they need compatibility with other GPL-2.0-only codebases, most notably the Linux kernel, which is licensed under GPL-2.0 rather than a later version.

Software distributed under GPL-2.0 cannot be resold or wrapped in ways that remove the source availability. You're free to sell copies or charge for support and hosting, but recipients must be able to get the source and must retain the same freedoms to modify and redistribute. Projects choose GPL-2.0 when they want strong guarantees that improvements to the code stay open, even at the cost of limiting adoption by companies unwilling to open-source what they build on top. OBS Studio and Jellyfin, both listed here, use GPL-2.0 for this reason.