You can add any custom Spigot plugin to your Code Kingdoms server, as long as it is compatible with the latest release of Minecraft.
Most bukkit plugins are Spigot compatible, as Spigot is a new version of bukkit after development discontinued on it.
To add a plugin follow these steps:
Click the plugin button on the right hand side of the code editor.
Enable the list of popular plugins we maintain, or upload your custom .jar plugin
Please remember some plugins may have bugs or interact oddly with other plugins which may cause your server to crash! If your server does start crashing, try disabling your custom plugins: https://downloads.intercomcdn.com/i/o/54686150/b5069a22e59533fa1cac149e/Screen+Shot+2018-04-06+at+09.21.46.png