Search for Xcode 6: Use the search bar to find specific iterations, such as Xcode 6.1.1 or Xcode 6.4, which was the final stable release of the 6.x series.
Should I help you find the specific for a particular version of OS X to run this?
Log in with your Apple ID: You do not need a paid developer account to access the archives, but a standard Apple ID is required.