A downhole indexing apparatus for cyclically varying a configuration or operational mode of a downhole tool according to a predetermined sequence, the apparatus comprising: a tubular body having a throughbore; an indexing member selectively moveable relative to the tubular body in response to a signal between two axial positions, a first position and a second position; where the movement of the indexing member relative to the tubular body is defined by an indexing pin and slot coupling arrangement; an indexing fluid chamber uphole of the indexing member; where the indexing fluid chamber is in fluid communication with the throughbore via an indexing chamber port; and where the signal for moving the indexing member comprises change in a differential fluid pressure acting across the indexing member; characterized in that the apparatus further is comprising: a balance piston for supporting the indexing member at at least one of the axial positions; wherein the indexing member is selectively movable between the first axial position and the second axial position in response to the signal, the second position comprising the supported position, and wherein the balance piston is configured to move from a passive position to an active position to support the indexing member at the second position; wherein the indexing member is biased towards the supported position by a biasing force, and the balance piston is configured to at least partially counteract the biasing force when the indexing member is in the supported position; where the balance piston is configured to engage or contact the indexing member at the second position, thereby reducing the load on the indexing member and consequently the indexing pin. a tubular body having a throughbore; an indexing member selectively moveable relative to the tubular body in response to a signal between two axial positions, a first position and a second position; where the movement of the indexing member relative to the tubular body is defined by an indexing pin and slot coupling arrangement; an indexing fluid chamber uphole of the indexing member; where the indexing fluid chamber is in fluid communication with the throughbore via an indexing chamber port; and where the signal for moving the indexing member comprises change in a differential fluid pressure acting across the indexing member; characterized in that the apparatus further is comprising: a balance piston for supporting the indexing member at at least one of the axial positions; wherein the indexing member is selectively movable between the first axial position and the second axial position in response to the signal, the second position comprising the supported position, and wherein the balance piston is configured to move from a passive position to an active position to support the indexing member at the second position; wherein the indexing member is biased towards the supported position by a biasing force, and the balance piston is configured to at least partially counteract the biasing force when the indexing member is in the supported position; where the balance piston is configured to engage or contact the indexing member at the second position, thereby reducing the load on the indexing member and consequently the indexing pin. a balance piston for supporting the indexing member at at least one of the axial positions; wherein the indexing member is selectively movable between the first axial position and the second axial position in response to the signal, the second position comprising the supported position, and wherein the balance piston is configured to move from a passive position to an active position to support the indexing member at the second position; wherein the indexing member is biased towards the supported position by a biasing force, and the balance piston is configured to at least partially counteract the biasing force when the indexing member is in the supported position; where the balance piston is configured to engage or contact the indexing member at the second position, thereby reducing the load on the indexing member and consequently the indexing pin.