Abstract: A window mounted temporary working platform which is totally assembled by one user from inside the window being repaired, maintained, or washed. The device provides a working platform at an elevation below the outer window sill with two side rails, an outer rail and a working platform which is supported without permanent installation on the building being serviced. The device is adjustable in width to accommodate a wide variety of window widths and is configured to provide for window with outer storm windows and window installation where the area below the inner sill is unavailable for platform support or connection due to of a heater or radiator.