A door closer, in particular a hinge door closer, including a locking function or free-swing function, having a door closer housing, an output shaft to be connected to a door, a piston assembly connected to the output shaft and guided in the door closer housing, a closer spring, a piston rod adapted to connect the piston assembly to the closer spring, a hydraulic lock compartment adapted to lock the closer spring, and in particular a free-swing assembly which is adapted to enable a translational motion of the piston assembly decoupled from the closer spring when the closer spring is locked.