A modular rail system for suspending sliding doors, including at least one rail profile having a top side arranged for being fixed against a horizontal wall part, a bottom side having a rail portion for carrying suspension wheels of a sliding door, a first lateral side arranged for being fixed against a vertical wall part, and an open second lateral side. On both opposite lateral sides the rail profile includes recesses having substantially the same shape for engaging complementary spacer elements. A sliding door system including a rail system, at least one sliding door with suspension wheels and at least one repositionable braking/stopping element having a stop for defining an extreme position of the sliding door and a releasable fixing element for fixing the braking/stopping element in the rail system. The fixing element is spaced a predetermined distance from the stop, chosen for maintaining user accessibility to the fixing element while the stop is located in a user inaccessible position.