You can clone with
HTTPS or Subversion.
The goal of this ticket is to provide a coherent useful set of Developer documentation that help developer make the most out of the open Piwik analytics platform.
Awesome work done by @capedfuzz
Check out the new developer website at: http://developer.piwik.org/
Guides, getting started, API reference docs
We will keep improving the website in the next few months.