Craftbukkit is the original API that allows for third party developers to add their own code to Minecraft.
For several years, Craftbukkit has been an amazing tool that allows for developers to create plugins for Minecraft and for server owners to alter the gameplay experience for end users.
Craftbukkit has since ceased development and is currently being maintained for the latest patches by SpigotMC. Although it is not currently being developed, it is still a great option for adding plugins to your server.
We provide several Craftbukkit releases for you to use for your server and we keep them updated regularly.