you can also just not accept code contributions from other people
> If you are happy to contribute code and then have them take it and sell it under a closed source license; or at a later stage just decide to relicense the whole thing as closed source; go for it. But most external contributors probably wouldn't like this.
bsd and mit licenses also allow this without a cla (that's the whole reason for using them instead of a strong copyleft like the gpl) and they seem to be very popular
> If you are happy to contribute code and then have them take it and sell it under a closed source license; or at a later stage just decide to relicense the whole thing as closed source; go for it. But most external contributors probably wouldn't like this.
bsd and mit licenses also allow this without a cla (that's the whole reason for using them instead of a strong copyleft like the gpl) and they seem to be very popular