Didn't see it mentioned here, see details about Developer Mode on http://developers.squarespace.com/initial-setup/. Don't know when it was first made available so it may be a recent addition. In short, squarespace offers SFTP access to the template code for your site. It also provides a GIT repo of the template code, nice! Note: I successfully used FileZilla to establish the SFTP connection, using sftp at command line would connect but was then immediately disconnected... didn't bother investigating further to figure out what was going on.
Just realized the sftp command line issue was I didn't include the site folder (as is mentioned in the page I referred to) So, setup... I used a ssh config file since I couldn't quickly figure out how to provide a username with an ampersand in it to sftp command line program. This example is good for GNU Linux, BSD etc will vary slightly for Windows. # ~/.ssh/config Host SQUARESPACE HostName dev.squarespace.com Port 2030 User your-user-name And then at the command line just run the following sftp command > sftp SQUARESPACE:/your-site-name