A platform system for leveling a stage includes at least two module assemblies, each including at least two receiving members being releasably secured to each other. At least two first supports are engaged and removably secured to the at least two receiving members, at least one receiving member present is not engaged or secured to a first support. Each first support includes an elongate portion, an extendible portion extendible from and lockingly engageable with the elongate portion, a base member removably attached to the extendible portion. A retention system is configured to engage and lockingly secure the extendible portion to form a first support of desired length, and at least one second support releasably connected to a first support and module assembly. The retention system is configured to rapidly extend and lockingly engage the extendible portion, the base member providing self-leveling of each of the module assemblies of the stage.