First install Anaconda Distribution and then, using the Anaconda prompt install Gitools with this command "conda install -c bbglab gitools" and run it with the command "gitools". It's also possible to add the channel bbglab to the Anaconda Navigator and then install and run Gitools directly from the navigator.
Oracle Java 7 or 8 must be installed on your machine in order to run Gitools. Current version of Gitools it is NOT working with Java 9.
To install Gitools uncompress the zip file and double click on gitools if you are a Mac OS X or Linux user or, if you are a Windows user, double click on gitools.exe.
Gitools is an open-source application, distributed under the license GPL-3. The project is hosted at Github where you can download and for the source code.