I’m a new user developing a site for a client, who insists on Sparkle. How can we both log in to build and manage a new Sparkle site?
Thanks,
Deb
Hey @GoodCitizen, welcome onboard! 
Sparkle is a close system that works on your Mac. So in a round about way you can build out the Sparkle project file and then share it in an iCloud folder where your client can access it by opening it in Sparkle on their end. The Sparkle they use must be the same Sparkle you use, for example Sparkle Pro.
You will need to introduce a file naming system, like maybe placing the date on the end?
When your client makes changes and saves it it will be saved to the shared folder so when you open the Sparkle project file you will see the latest changes made by your client. This will also be the case the other way around.