Planning tool for TSO-DSO shared technologies. The tool is focused on the planning of shared ESSs that can simultaneously be used by TSO and DSOs. It is considered that the investment in the shared ESSs is performed by a third-party investor, the Energy Storage System Owner (ESSO), that can participate in energy and secondary reserve markets. The outcome of the tool is an adaptive investment plan in shared ESSs to be installed at the boundary nodes (primary substations) between the transmission and distribution networks participating in the coordination scheme. The tool considers the coordination scheme proposed in ATTEST, that was extended to consider the presence of shared resources. Further details regarding ATTEST's TSO-DSO coordination mechanism are provided in D2.4 (available in the ATTEST's project page). This program is free software: you can redistribute it and/or modify it under the terms of the European Union Public Licence v1.2 as published by the European Union.