Heat exchanger comprising a central body with a first set of channels (A ij) forming part of a first set of fluid pathways (P 1 a, P 1 b) through the heat exchanger, and a second set of channels (B ij) forming part of a second set of fluid pathways (P 2 a, P 2 b) through the heat exchanger, the channels (A ij, B ij) extending from a first end of the central body, along a main direction through the central body, to a second end of the central body, wherein, in the central body, in a cross-section across the main direction, the channels (A ij, B ij) of the first and second sets form a checkered pattern by being arranged alternatingly in a plurality of rows (X 1X, X 2X, X 3X, X 4X, X 5X, X 6X, X 7X, Xsx) along a first direction (T 1) extending along a first perimeter of the pattern and alternatingly in a plurality of rows (Y 1, Y 2, Y 3, Y 4, Y 5, Y 6, Y 7, Y 8) along a second direction (T 2) extending transverse to the first direction (T 1) and along a second perimeter of the pattern, the heat exchanger further comprising two inner transition portions of which one extends from the first end of the central body and one extends from the second end of the central body, the channels (A ij, B ij) of the central body extending from the ends (10a, 10b) of the central body, in the checkered pattern and into each of the inner transition portions at an inner end of respective inner transition portion, through respective inner transition portion and to an outer end of respective inner transition portion, wherein, in respective inner transition portion, every second row (X 2X, X 4X, X 6X, X 8X) of the rows (X 1X, X 2X, X 3X, X 4X, X 5X, X 6X, X 7X, X 8X) along the first direction (T 1) is increasingly shifted in the first direction (T 1) and relative every other second row (X 1X, X 3X, X 5X, X 7X) of the rows (X 1X, X 2X, X 3X, X 4X, X 5X, X 6X, X 7X, X 8X), until the checkered pattern of the first and the second sets of channels (A ij, B ij) at the inner end of respective inner transition portion is transformed into a line pattern at the outer end of respective inner transition portion, the channels of the respective set of channels (A ij, B ij) thereby, at each outer end of respective inner transition portion, being arranged alongside each other in rows that extend along the second direction (T 2), with the rows of the first set channels (A ij) and the rows of the second set channels (B ij) being arranged alternatingly along the first direction (T 1), wherein the heat exchanger further comprises two outer transition portions, one extending from either outer end of respective inner transition portion, wherein each outer transition portion comprises a first set of channels (A ij) forming part of the first set of fluid pathways (P 1) and a second set of channels (B ij) forming part of the second set of fluid pathways (P 2), wherein the channels (A ij, B ij) of the first and second set extend from an inner end of the outer transition portion, facing the inner transition portion, through the outer transition portion and out of the outer transition portion, characterized in that, in the outer transition portions, the first set of channels (A ij) and/or the second set of channels (B ij) are diverted to extend along a third direction (T 3) respectively a fourth direction (T 4) extending in parallel with a diversion plane defined by the main direction and the second direction (T 2) and being transverse to said shift direction (T 1) of respective inner transition portion, wherein the third and fourth directions (T 3, T 4) are different from each other such that the first set of channels (A ij) extend out of the outer transition portion at a first end portion and the second set of channels (B ij) extend out of the outer transition portion at a second end portion, the second end portion being separated from the first end portion. a first set of channels (A ij) forming part of a first set of fluid pathways (P 1 a, P 1 b) through the heat exchanger, and a second set of channels (B ij) forming part of a second set of fluid pathways (P 2 a, P 2 b) through the heat exchanger, the channels (A ij, B ij) extending from a first end of the central body, along a main direction through the central body, to a second end of the central body,