The invention relates to a modular rail system for suspending sliding doors, comprising at least one rail profile comprising 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 comprises recesses having substantially the same shape for engaging complementary spacer elements. The invention further relates to a sliding door system comprising a rail system, at least one sliding door with suspension wheels and at least one repositionable braking/stopping element comprising 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.