It took a while, but XKit is now once again available for Safari users.
This version is a near-complete rewrite of the old version, so if you currently have XKit on Safari, please uninstall it before installing this version.
I’ve tested it on Safari 8 and as far as I know there aren’t any Safari-related bugs left, but as always it is provided without any support.
I couldn’t test it on Safari 8 since Apple only allows one version per computer, so I’m not sure if it runs on Safari 7. Please let me know if it runs on Safari 7 or not. (And if it does not, you can re-download the old version here)