I'd also be interested in the legal ramifications of withholding source code. Don't take my advice without consulting legal sources because I'm NOT a lawyer. Still, I don't see how you can be sued for not delivering something for which you were never paid.
If they never pay you, perhaps you could open source the project and use it to advertise yourself.
i wish it was that simple. there are 2 parts website and mobile apps, obviously with just the mobile apps src code, people cant do much with it.
Someone in news.ycombinator here must have dealt with this problem or at least a number of people, I know we usually only read successful stories everywhere but there actually thousands that dont make it
If they never pay you, perhaps you could open source the project and use it to advertise yourself.