Hilda is a modular Discord bot framework that sits on top of JDA. You can easily create plugins that interface with Hilda.

Commands for the bot administrators

Ping pong

Vote manager

Modify channel order based on user count

Allows self-granting of roles

Remind users about things so they don't forget

React to iconic messages to have them saved to a configurable channel

Queue and play audio

Sends a message when a new user joins