Under US copyright law, the person who creates a work generally owns it. An independent contractor is not an employee, so the work made for hire doctrine usually does not apply to them by default.
That means without a written assignment, the developer who built your product may hold the copyright in it. Companies discover this during diligence, at the worst possible moment, when an investor asks for proof of the chain of title.
The fix is straightforward and belongs in every contractor agreement: a present assignment of all right, title and interest, plus a covenant to sign anything further that is needed to record it.
