I intend to share my source code on an invite-only basis to a few dozen users maybe. The source code itself should not be public. Participants are allowed and encouraged to subm
Bitbucket - Their plans seem to be the best. They give you way more than GitHub do for free accounts - in fact, I'm still only using the free plan - no need to sign up to the paid ones; plus the interface is almost identical to GitHub.
A repository on Bitbucket can have up to five private users with unlimited public or private repositories - the only thing you seem to be paying for with the paid accounts are more users to access your private repositories.