SketchUp was developed by startup company @Last Software of Boulder, Colorado, co-founded in 1999 by Brad Schell and Joe Esch. SketchUp debuted in August 2000 as a general purpose 3D content creation tool, with the tagline "3D for Everyone"
Google acquired @Last Software on March 14, 2006, attracted by @Last's Software's work developing a plugin for Google Earth. SketchUp is currently owned by Trimble Navigation, who acquired it from Google in June 2012.
Sketchup Make (formerly SketchUp for Home and Personal Use), is for non-commercial use and is available as freeware. The more advanced Sketchup Pro, for professional use, is a paid product. It currently runs in Windows and OS X, and is available in a variety of languages.
(wiki entry courtesy The Wikipedia )