Parcels are the smallest units of land usually considered for urban development purposes. Analyses at the parcel level allow taking into account the administrative and physical environment of buildings with accuracy (roads, surrounding buildings, local design rules for building construction). In this article, we propose a free and open source software application, namely Parcel Manager, whose aims are twofold: 1) to assess the effects of different parcel reshaping rules and planning principles on the location, the number and the shape of reshaped parcels, and 2) to provide a basis to assess the potentials for new building constructions. To this end, Parcel Manager simulates a large variety of parcel reshaping processes, with or without the joint creation of new roads, and produces realistic parcel layouts that represent either infill urban developments, edge expansions or leapfrog developments. It can be used to determine if the densification of built parcels is feasible or not, regarding planning and design rules as well as the current urban fabric. The current version of Parcel Manager only concerns the reshaping of parcels dedicated to the construction of residential buildings but not other types buildings.