PixelVip is a plugin to manage vip on your server with easy commands, easy configuration and a lot of features.
Spigot: https://www.spigotmc.org/resources/pixelvip.30438/
Bukkit: https://dev.bukkit.org/projects/pixelvip
Sponge: https://ore.spongepowered.org/FabioZumbi12/PixelVip
See commands, API and bungee usage: https://github.com/FabioZumbi12/PixelVip/wiki
The source is available on GitHub: https://github.com/FabioZumbi12/PixelVip