when we find a GPL-3.0 license project on github.com, The project is BBS tool, it has the theme option. If we write our own theme. do we need to make our theme (source code) for that project public available? because of source code availability of GPL-3.0.
Also that project the ability to install plugins. If we write our own plugins, do we need to follow the license compatibility of GPL, for our own plugins ? making our plugin source code public available? Thank you.
It depends on your usage.
Keep in mind that even if you have to publish these themes/plugins etc. under the GNU GPL, you can choose any GNU GPL compatible license (eg MIT).
If you use the theme on your server, it is also debatable whether you need to share it at all. For example, Wordpress users do not post the source code for all parts of Wordpress, even though it is GNU GPLed details here.
It also depends on how the software is built.
See these parts from the FSF FAQ: https://www.gnu.org/licenses/gpl-faq.html#GPLPlugins
https://www.gnu.org/licenses/gpl-faq.html#GPLAndPlugins
Note that even if you must publish your theme or plugin, it only applies when you distribute these works. You may freely use them for internal use.
Edit: If you specify what kind of software it is, I'll be able to help you more.
Also, don't hesitate to ask questions or contact me directly.
This is not legal advice
