A transformable ladder system with adjustable level comprising a first ladder plane comprising uprights (111, 111') and at least two rungs, a second ladder plane comprising uprights (112, 112') and rungs, and at least one articulation device (103, 103') between the first ladder plane and the second ladder plane, the transformable ladder system being movable between a so-called open state in which the first ladder plane and the second ladder plane form a non-zero angle and a so-called closed state in which the first ladder plane and the second ladder plane are parallel or substantially parallel to one another, the articulation device (103, 103') being mounted on one of the uprights (111, 111') of the first ladder plane, and receiving one of the uprights (112, 112') of the second ladder plane, the articulation device (103, 103') comprising a passage opening for the second ladder plane through the top of the articulation device (103, 103'), from the open state, along a direction parallel or substantially parallel to a longitudinal direction of the second ladder plane when the system is in the open state, and the articulation device (103, 103') comprising a locking housing of a rung of the second ladder plane when the second ladder plane is moved upward in said direction from the open state, one among the articulation device (103, 103') and the upright (112, 112') of the second ladder plane received by the articulation device (103, 103') comprising a stud, and the other among said articulation device (103, 103') and said upright (112, 112') comprising a wall for guiding the stud toward a first location of this wall, when the stud is positioned in the first location of the wall the ladder system being in the open state, the transformable ladder system comprising a second location for positioning the stud, when the stud is positioned in the second location the ladder system being in the closed state, when the upright (112, 112') of the second ladder plane received by the articulation device (103, 103') rests on the articulation device (103, 103') and is pivoted to transition the transformable ladder system from the closed state to the open state, the stud bears or comes to bear against the wall, the ladder system being characterized in that the wall is continuous between the first location and the second location. the articulation device (103, 103') being mounted on one of the uprights (111, 111') of the first ladder plane, and receiving one of the uprights (112, 112') of the second ladder plane, the articulation device (103, 103') comprising a passage opening for the second ladder plane through the top of the articulation device (103, 103'), from the open state, along a direction parallel or substantially parallel to a longitudinal direction of the second ladder plane when the system is in the open state, and the articulation device (103, 103') comprising a locking housing of a rung of the second ladder plane when the second ladder plane is moved upward in said direction from the open state, one among the articulation device (103, 103') and the upright (112, 112') of the second ladder plane received by the articulation device (103, 103') comprising a stud, and the other among said articulation device (103, 103') and said upright (112, 112') comprising a wall for guiding the stud toward a first location of this wall, when the stud is positioned in the first location of the wall the ladder system being in the open state, the transformable ladder system comprising a second location for positioning the stud, when the stud is positioned in the second location the ladder system being in the closed state, when the upright (112, 112') of the second ladder plane received by the articulation device (103, 103') rests on the articulation device (103, 103') and is pivoted to transition the transformable ladder system from the closed state to the open state, the stud bears or comes to bear against the wall, the ladder system being characterized in that the wall is continuous between the first location and the second location.