Abstract: A heat exchanger (100) having a plurality of plates (101) manufactured preferably but not limiting to the stamping process, the plates has been configured to accommodate the internal fins (106). The plates (101) also define plurality of the passages (102) for flowing at least two fluids. A plurality of conduits (103) fluidly coupled to a first end and second of the end of the plates (101) which allows the flow of the fluids. At least one inlet (104) coupled to a first end, and at least one outlet (105) coupled to the second end of the plurality of plates (101) configured to allow the flow of the fluids wherein each fluid flow in a different direction from the other, a plurality of inner fins (106) disposed on a surface of each of the plurality of plates (101) for increasing the surface to volume ratio of the first and second fluid to achieve pre-defined thermal performance.