We study the freeness of the group \(\textrm{Inv}(D)\) of invertible ideals of an integral domain D, and the freeness of some related groups of (fractional) ideals. We study the relation between \(\textrm{Inv}(D)\) and \(\textrm{Inv}(D_P)\) , in particular in the locally finite case, and we analyze in more detail the case where D is Noetherian (obtaining a characterization of when \(\textrm{Inv}(D)\) is free for one-dimensional analytically unramified Noetherian domains) and where D is Prüfer.