A system includes an online shopping platform, a ingredient database assembly and a control unit. The control unit transmits to the online shopping platform entries of active ingredient data and preservative ingredient data respectively corresponding to an active ingredient and a preservative ingredient and respectively stored in an active ingredient database and a preservative ingredient database of the ingredient database assembly, for allowing selection of at least one of the entries via the online shopping platform to result in a desired formula. The desired formula is used for subsequent production of a customized ingredient composition when it is determined that the desired formula conforms with rules of formulation.