The invention concerns a modular backpack with several carrying systems. Known modular backpacks have only one carrying system. Furthermore, their modularity is limited because the modules can only be arranged horizontally or vertically. The invention consists of at least three modules that can be arranged horizontally one above the other and vertically one behind the other and can be detachably connected in pairs (100). Each module or combination of these is equipped in such a way that it can be attached to at least two carrier systems. Carrying system A (200) is dimensioned so that the user can carry the weight of the maximum possible number of modules comfortably. Carrying system A has at least one horizontal support element (202) which is detachably attached to the carrying system, can be attached at different heights and can be swiveled away from one side of the carrying system (203). To fasten the modules, mounting elements (205) are fitted in their backs, which can accommodate the plug-in elements of carrier system A in a form-fit manner. Carrying system B is dimensioned so that the user can comfortably carry at least one module. It consists of at least one carrying strap which can be detachably attached to both sides of each module or a combination of both. The invention can be used by many users and applications due to its improved modularity and constant wearing comfort. The ideal customer group are people who have an active live, needing day-packs, photography bags as well as hiking backpacks.