Folding clasp for a bracelet, comprising: - a first blade and at least a second blade, articulated with respect to each other, the second blade comprising two lateral beams (14, 14'); - a first fixing member connected to the first blade and destined to be connected to a first free end of the bracelet; - a second fixing member destined to be connected to a second free end of the bracelet; - a locking mechanism arranged to hold said first and second blades (1, 2) in the closed position of the clasp when said first and second blades (1, 2) are brought together and folded over one another, - a central support structure connected to said first blade or forming a single piece with said first blade; - a device for adjusting the length of the bracelet, integrated and/or mounted in said central structure, the adjustment device comprising: - a mobile part to which said first fixing member is attached, said mobile part being arranged on said support structure so as to be able to move longitudinally in relation to the bracelet in order to perform a length adjustment; - a blocking device (33, 34, 37) arranged to block the movement of the mobile part in at least one longitudinal movement direction; - an actuating member arranged to allow the unblocking of the blocking device and the movement of the mobile part and thus the length adjustment; - wherein said mobile part is housed inside a free end of said central structure so as to be able to emerge from said end or be inserted into said end during said longitudinal movement; the clasp being characterized in that said lateral beams (14, 14') of said second blade are arranged laterally with respect to said central support structure when the clasp is closed. - a first blade and at least a second blade, articulated with respect to each other, the second blade comprising two lateral beams (14, 14'); - a first fixing member connected to the first blade and destined to be connected to a first free end of the bracelet; - a second fixing member destined to be connected to a second free end of the bracelet; - a locking mechanism arranged to hold said first and second blades (1, 2) in the closed position of the clasp when said first and second blades (1, 2) are brought together and folded over one another, - a central support structure connected to said first blade or forming a single piece with said first blade; - a device for adjusting the length of the bracelet, integrated and/or mounted in said central structure, the adjustment device comprising: - a mobile part to which said first fixing member is attached, said mobile part being arranged on said support structure so as to be able to move longitudinally in relation to the bracelet in order to perform a length adjustment; - a blocking device (33, 34, 37) arranged to block the movement of the mobile part in at least one longitudinal movement direction; - an actuating member arranged to allow the unblocking of the blocking device and the movement of the mobile part and thus the length adjustment; - wherein said mobile part is housed inside a free end of said central structure so as to be able to emerge from said end or be inserted into said end during said longitudinal movement; - a mobile part to which said first fixing member is attached, said mobile part being arranged on said support structure so as to be able to move longitudinally in relation to the bracelet in order to perform a length adjustment; - a blocking device (33, 34, 37) arranged to block the movement of the mobile part in at least one longitudinal movement direction; - an actuating member arranged to allow the unblocking of the blocking device and the movement of the mobile part and thus the length adjustment; - wherein said mobile part is housed inside a free end of said central structure so as to be able to emerge from said end or be inserted into said end during said longitudinal movement;