[pacino]

What’s the license that bbpress is using? GPL?

And, I am wondering whether it is possible to use bbpress (with some modification) in a commercial website and open source only the modified bbpress (that is, the rest of the website will not be open sourced)?

Thanks

[Sam Bauers]

bbPress is released under the GPL v.2

Unless you plan to redistribute (i.e. give away or sell) your modified code, you are under no obligation to release your modified source code.