The Geometer's Sketchpad is a product of the Key Curriculum Press. Click here for the homepage of the software, where you can download the Instructor's Evaluation Edition (this is demo of the software for your evaluation, up to 60 days and cannot be re-installed). You cannot save or print your work with the evaluation edition.
Download also the workshop guide for a comprehensive introduction of the software from the publisher.

Files created with The Geometer's Sketchpad have extension .gsp in the file name. You may download sample files provided in this site and open with your Sketchpad program or the Evaluation Edition.

Some Sketchpad files can be converted to Java applets and can be opened with ordinary Java enabled browsers without the Sketchpad program. See the page Transformation in GSP for some examples of JavaSketchpad files. The official JavaSketchpad homepage is here.

Search the web with the keywords: geometer's sketchpad, 幾何畫板  or  互動幾何 for info about more resources online.

List of GSP and dynamic geometry books