You can manage your Drupal code in Cloud Platform using Git, a version control system (VCS). You can use the command-line versions of Git or various GUI tools that include open source, commercial IDE plugins, or GUI clients.

Learn about Using Git with Cloud Platform.

After you configure your environment to work with the code repository that you’ll use to manage your codebase on Cloud Platform, you can check out a local copy of your codebase from the remote code repository.